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Chapter 2. Test Procedures for Packages Labeled by Weight – 

Gravimetric Testing 

2.1. Scope 

The gravimetric test method uses weight measurement to determine the net quantity of contents of packaged 

goods. This chapter includes general test methods to determine the net quantity of contents of packages 

labeled in terms of weight. Gravimetric testing is the preferred method of testing most products because it 

reduces destructive testing and improves measurement accuracy. 

Note: If Multiunit or Variety Packages are to be inspected, refer to Chapter 5. “Specialized Test

Procedures” for guidance in testing. If a total quantity declaration is being verified and the MAV to be 

applied is not based on a percentage of the labeled quantity, refer to Section 1.2.4.1. “Total Quantity MAV 

for Multiunit and Variety Packages.” 

(Note Added 2022) 

2.2. Measurement Standards and Test Equipment 

Scale Requirements 

Use a scale (for this handbook the term “scale” includes balances) that has at least 100 scale divisions. 

It must have a load-receiving element of sufficient size and capacity to hold the packages during 

weighing. It also requires a scale division no larger than 1

/6 of the Maximum Allowable Variation

(MAV) for the package size being weighed. The MAV/6 requirement ensures that the scale has 

adequate resolution to determine the net contents of the packages. Subsequent references to product 

test results requiring the agreement to within one scale division are based on scale divisions that are 

equal to or only slightly smaller than the MAV/6. (see Appendix A, Table 2-5. “Maximum Allowable 

Variations (MAVs) for Packages Labeled by Weight.”)

Example: 

The MAV for packages labeled with a net weight 113 g (0.25 lb) is 7.2 g (0.016 lb). Divide (÷) the 

MAV by 6 to obtain the maximum scale division that can be used to determine the gross, tare and 

net weights for a package size.

7.2 g (0.016) ÷ 6 = 1.2 g (0.002 lb) 

In this example, a 1 g (0.002 lb) scale division would be the maximum scale division 

appropriate for weighing these packages.

(Amended 2010) 

Scale Accuracy

Verify the accuracy of a scale before each initial daily use, each use at a new location, or when there is 

any indication of abnormal equipment performance (e.g., erratic indications). Recheck the scale 
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accuracy if it is found that the sample does not pass, so there can be confidence that the test equipment 

is not at fault.

Scales used to check packages must meet the acceptance tolerances specified for their accuracy class 

in the current edition of NIST Handbook 44 (HB 44) “Specifications, Tolerances, and Other Technical 

Requirements for Weighing and Measuring Devices.” The tolerances for Class II and Class III scales 

are presented in NIST HB 44, Section 2.20. Scales, “T.N. Tolerances Applicable to Devices Marked I, 

II, III, III L, and IIII.”

Note: If the package checking scale is not marked with a “class” designation, use Table 2-1. “Class of 

Scale” to determine the applicable tolerance.

Always use good weighing and measuring practices. For example, be sure to use weighing and 

measuring equipment according to the manufacturer’s instructions and make sure the environment is 

suitable. Place scales and other measuring equipment (e.g., flasks and volumetric measures) on a rigid 

support and maintain them in a level condition if being level is required to ensure accuracy.

Scale Tolerance

Follow this procedure to determine the scale tolerance:

1. Determine the total number of divisions (i.e., the minimum increment or graduation 

indicated by the scale) of the scale by dividing the scale’s capacity by the minimum division.

Example:

A scale with a capacity of 5000 g and a minimum division of 0.1 g has 50 000 

divisions.

5000 ÷ 0.1 g = 50 000 division

2. From Table 2-1. “Class of Scale”, determine the class of the scale using the minimum scale 

division and the maximum number of scale divisions.

Example: 

On a scale with a minimum division of 0.1 g and 50 000 total scale divisions the 

appropriate class is “II.”

Note: If a scale is used where the number of scale divisions is between 5001 and 10 000 and the 

division size is 0.1 g or greater and is not marked with an accuracy Class II marking, Class III 

scale tolerances apply.

3. Determine the number of divisions for any test load by dividing the value of the mass 

standard being applied by the minimum division indicated by the scale.

4. Determine the tolerance from Table 2-2. “Acceptance Tolerances for Class of Scale Based 

on Test Load in Divisions” in divisions appropriate for the test load and class of scale

Example: 

If the scale has a minimum division of 0.1 g and a 1500 g mass standard is applied, 

the test load is equal to 15 000 divisions (1500/0.1). On a Class II scale with a test 

load between 5001 and 20 000 divisions, Table 2-2. “Acceptance Tolerances for 
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Class of Scale Based on Test Load in Divisions” indicates the tolerance is plus or 

minus one division.

Table 2-1.

Class of Scale

Value of Scale Division1

Minimum and Maximum Number of 

Divisions Class of Scale

Minimum Maximum

1 mg to 0.05 g 100 100 000 II

0.1 g or more 5000 100 000 II

0.1 g to 2 g

0.000 2 lb to 0.005 lb

0.005 oz to 0.125 oz

100 10 000 III

5 g or more

0.01 lb or more

0.25 oz or more

500 10 000 III

1

On some scales, manufacturers designated and marked the scale with a verification division (e) for 

testing purposes (e = 1 g and d = 0.1 g). For scales marked Class II, the verification division is larger 

than the minimum displayed division. The minimum displayed division must be differentiated from the 

verification scale division by an auxiliary reading means such as a vernier, rider, or at least a significant 

digit that is differentiated by size, shape, or color. Where the verification division is less than or equal 

to the minimum division, use the verification division instead of the minimum division. Where scales 

are made for use with mass standards (e.g., an equal arm balance without graduations on the indicator), 

the smallest mass standard used for the measurement is the minimum division.

Table 2-2.

Acceptance Tolerances for Class of Scale Based on Test Load in Divisions

Test Load in Divisions

Tolerance

Class II Scale Class III Scale

0 to 5000 0 to 500 Plus or Minus 0.5 Division

5001 to 20 000 501 to 2000 Plus or Minus 1.0 Division

20 001 or more 2001 to 4000 Plus or Minus 1.5 Divisions

Not Applicable 4001 or more Plus or Minus 2.5 Divisions

Scale Verification

Use the following procedures to verify the scale. These procedures, which are based on those required 

in NIST Handbook 44, have been modified to reduce the amount of time required for testing scales in 

field situations.
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Do not use a scale if it has an error that exceeds the specified tolerance in Table 2-2. “Acceptance 

Tolerances for Class of Scale Based on Test Load in Divisions” in any of the performance tests 

described in the following section.

2.2.4.1. Increasing-Load Test

Use certified mass standards to conduct an “increasing-load test” with all test loads centered on the 

load-receiving element. Start the test with the device on zero and progress with increasing test 

loads to a “maximum test load” of at least 10 % more than the gross weight of the packages to be 

tested. Use at least three different test loads of approximately equal value to test the device up to 

the “maximum test load.” Verify the accuracy of the device at each test load. Include the package 

tare weight as one of the test points.

2.2.4.2. Decreasing-Load Test

For all types of scales, other than one with a beam indicator or equal-arm balance, conduct a 

“decreasing-load test” with all test loads centered on the load-receiving element. Use the same test 

loads used in the “increasing-load test” of this section, and start at the “maximum test load.” 

Remove the test loads in the reverse order of the increasing-load test until all test loads are removed. 

Verify the accuracy of the scale at each test load.

2.2.4.3. Shift Test

When conducting a Shift Test on Bench Scales or Balances, use a test load equal to one-third of 

the “maximum test load” used for the “increasing-load test.” For bench scales (see Figure 2-1. 

“Bench Scales or Balances”) apply the test load as nearly as possible at the center of each quadrant 

of the load receiving element as shown in Figure 2-1. “Bench Scale or Balances.”

For Equal-Arm Balances, use a test load equal to one-half capacity centered successively at four 

points positioned equidistance between the center and the front, left, back, and right edges of each 

pan as shown (see Figure 2-2. “Equal-Arm Balance”). For example, where the load-receiving 

element is a rectangular or circular shape, place the test load in the center of the area represented 

by the shaded area.

 

Position 

1

Position 

2

Position 

4

Position 

3

Figure 2-1. Bench Scales or Balances Figure 2-2. Equal-Arm Balance

(Amended 2010)
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2.2.4.4. Return to Zero

Conduct the return to zero test whenever all the test weights from the scale are removed; check to 

ensure that it returns to a zero indication.

Other Test Equipment Requirements

Specifications, tolerances, and other technical requirements for the other measurement standards and 

test equipment cited in this handbook are specified in the following NIST publications. These 

publications may be obtained from the Office of Weights and Measures (www.nist.gov/pml/weightsand-measures/publications/nist-handbooks/other-nist-handbooks/other-nist-handbooks-2).

1. Mass Standards – Use NIST Handbook 105-1, “Specifications and Tolerances for Field 

Standard Weights” (2019)

2. Volumetric Flasks and Cylinders – Use NIST Handbook 105-2, “Specifications and Tolerances 

for Reference Standards and Field Standard Weights and Measures – Field Standard Measuring 

Flasks” (1996)

3. Stopwatches – Use NIST Handbook 105-5, “Specifications and Tolerances for Reference 

Standards and Field Standard Weights and Measures – Field Standard Stopwatches” (1997)

4. Thermometers – Use NIST Handbook 105-6, “Specifications and Tolerances for Reference 

Standards and Field Standard Weights and Measures – Specifications and Tolerances for 

Thermometers” (1997)

2.3. Basic Test Procedure for Gravimetric Testing of Net Weight

The following steps apply when gravimetrically testing any type of packaged product except borax and 

glazed or frozen foods. If the tested products contain borax, refer to Section 2.4. “Borax.” If encased-inice or ice glazed food is tested, refer to Section 2.6. “Determining the Net Weight of Encased-in-Ice and 

Ice Glazed Products.”

 Identify and define the inspection lot.

 Select the sampling plan.

 Record inspection data using an official inspection report.

 Select the random sample.

 Select and determine tare.

 Determine nominal gross weight and package errors.

 Evaluate compliance with the Maximum Allowable Variation (MAV) requirement and the 

average requirement.

Each step will be described in more detail in the following sections.
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Define the Inspection Lot

The official defines which packages are to be tested and the size of the inspection lot. The lot may be 

smaller or larger than the production lot defined by the packer. Only take action on the packages 

contained in the lot that has been defined.

Lots may be made up of either standard or random weight packages. Standard packages are those with 

identical net content declarations such as containers of soda in 2 L bottles and 2.26 kg (5 lb) packages 

of flour. “Random packages” are those with differing or no fixed pattern of weight, such as packages 

of meat, poultry, fish, or cheese.

Notes: 

(1) Normally, there will never be access to the entire “production lot” from a manufacturer. The 

“inspection lot” is selected from packages that are available for inspection/test at any location in 

the distribution chain.

(2) When packages are tested in retail stores, it is not necessary to sort by lot code. If lot codes are 

mixed during retail testing, be sure to record the lot codes for all of the packages included in the 

sample so that the inspector and other interested parties can follow up on the information. For 

special reasons, such as a large number of packages or the prior history of problems with the 

product or store, the inspector may choose to define a lot as only one type of packaged product 

(e.g., ground beef). Another reason to narrowly define the lot is if the results of an audit test 

indicate the possibility of a shortage in one particular lot code within a particular product.

Example: 

An inspection lot should consist of all of the cans of a single brand of peach halves, labeled 

with a net quantity of 453 g (1 lb). 

Select Sampling Plans

This handbook contains two sampling plans used to inspect packages: “Category A” and “Category B.” 

Use the “Category B” Sampling Plans to test meat and poultry products at point-of-pack locations that 

are subject to U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) 

requirements. When testing all other packages, use the “Category A” Sampling Plan.

Use Appendix A, Table 2-1. “Sampling Plans for Category A,” to conduct “Category A” inspections.

Use Appendix A, Table 2-2. “Sampling Plans for Category B,” to conduct “Category B” inspections.

Record Inspection Data

Use an official inspection report to record information. Attach additional worksheets, test notes, and 

other information as needed. This handbook provides random and standard packaged products model 

inspection report forms in Appendix C, “Model Inspection Report Forms.” (Refer to Appendix C for 

instructions on how to complete the forms’ box numbers.) Modify the model reports and the box 

numbers to meet your agency’s needs. Other formats that contain more or less information may be 

acceptable. The procedure below describes how to record inspection data using the “Model Inspection 

Report Forms” in Appendix C. The same information should be recorded regardless of the form used.

Note: Inspection reports should be legible and complete. Good recordkeeping practices typically 
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include record retention for a specified period of time.

2.3.3.1. Procedure for Recording Data

1. Record the product identity, packaging description, lot code, location of test, and other 

pertinent data.

2. Record the labeled net quantity of contents in Box 1. Record both metric and U.S. 

customary declarations if they are provided on the package label.

Example: 

If the labeled weight is 453 g (1 lb), record this in Box 1.

Note: When the declaration of net quantity on the package includes both the International 

System of Units (SI) (metric) and U.S. customary units, the larger of the two declarations 

must be verified. The rounding rules in NIST Handbook 130, Uniform Packaging and

Labeling Regulations permit packers to round declarations up or down based on their 

knowledge of their package filling targets and the accuracy of packaging equipment.

3. Determine the larger of the values by converting the SI declaration to U.S. customary

units, or vice versa, using conversion factors that are accurate to at least six places. 

Compare the values, and use the larger value in computing the nominal gross weight (see 

later steps). Indicate on the report which of the declarations is being verified when 

packages labeled with two units of measure are encountered.

Example: 

If the net weight declared on a package is 1 lb, the metric equivalent (accurate to six 

significant digits) is 453.592 g. Do not round down or truncate values in the 

calculations until the nominal gross weight is determined and recorded. If the 

package is labeled 454 g, then the metric declaration is larger than the U.S. 

customary declaration and should be used to verify the net contents of the package. 

4. Record the unit of measure in Box 2. The unit of measure is the minimum division of the 

unit of measurement used to conduct the test. If a scale is used that reads to thousandths 

of a pound, the unit of measure is 0.001 lb even if the scale division is 0.002 lb or 0.005 lb.

Examples: 

If the scale has a scale division of 0.5 g, the unit of measure is 0.1 g. If a weighed 

package that has an error of “− 0.5 g,” record the error as “− 5” using 

“dimensionless units.”

− 0.5 g ÷ 0.1 = 5 dimensionless units

If the scale indicates in increments of 0.002 lb, the unit of measure is 0.001 lb. If 

a weighed package has an error of “+ 0.016,” record the error as “+ 16” using 

“dimensionless units.” 

0.016 lb ÷ 0.001 = 16 dimensionless units
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Notes:

(1) When using dimensionless units, multiply package errors by the unit of measure 

to obtain the package error in weight.

(2) The Basic Test Procedure does not prohibit the use of units of weight instead of 

dimensionless units when recording package errors, nor does it prohibit the use 

of software programs to determine product compliance. Refer to Appendix F. 

“Glossary,” for the definition of dimensionless units.

5. Enter the appropriate MAV value in Box 3 for the type of package (weight, volume, etc.), 

the labeled net contents, and the unit of measure using Appendix A. Tables 2-5 through 

2-10.

6. Determine the MAV in dimensionless units and record in Box 4 on the Standard Package 

Report Form (a dimensionless unit is obtained by dividing the MAV recorded in Box 3 

by the unit of measure recorded in Box 2).

7. Determine how many minus package errors are permitted to exceed the MAV, (errors 

known as unreasonable minus errors [UMEs]), see Column 4 in either Table 2-1. 

“Sampling Plans for Category A” or Table 2-2. “Sampling Plans for Category B” (refer 

to Appendix A). Record this number in Box 8.

Random Sample Selection

It is important to select a random sample when conducting an official package inspection. Follow the 

steps below to select your sample. If the sample packages for the sample are not randomly selected, the 

test results may not be statistically valid.

1. Count the number of packages comprising the inspection lot or estimate the size to within 

5 % and record the inspection lot size in Box 5. 

2. Determine sample size using Appendix A, Table 2-1, “Sampling Plans for Category A” or 

Table 2-2, “Sampling Plans for Category B.” In Column 1, find the size of the inspection lot 

(the number recorded in Box 5 of the report form). Read across from Column 1 to find the 

appropriate sample size in Column 2 and record this number in Box 6 of the report form.

3. Randomly select a sample from the inspection lot. Random number tables (see Appendix B. 

“Random Number Tables”) or a calculator that is able to generate random numbers may be 

used to identify the sample.

Note: If the inspector and the party that is ultimately responsible for the packing and declaration of net 

weight for the product agree to an alternative method of sample selection, document how the sample 

packages were selected as part of the inspection record.

Procedures for Determining Tare 

There are three types of tare for the inspection of packaged goods. The tare weight may vary 

considerably from package to package as compared with the variability of the package net contents, 

even for packages in the same production lot. The basic test procedure in this handbook considers the 

variation for all tare materials.
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Used Dry Tare is used tare material that has been air dried, or dried in some manner to simulate the 

unused tare weight. It includes all packaging materials that can be separated from the packaged 

product, either readily (e.g., by shaking) or by washing, scraping, ambient air drying, or other 

techniques involving more than “normal” household recovery procedures, but not including 

laboratory procedures like oven drying. Labels, wire closures, staples, prizes, decorations, and 

such are considered tare. Used Dry Tare is available regardless of where the packages are tested. 

The net content verification procedures described in this handbook reference Used Dry Tare.

Note: When testing frozen foods with Used Dry Tare, the frost found inside frozen food packages 

is included as part of the net contents, except in instances in which glazed or frozen foods are tested 

according to Section 2.6. “Net Weight of Encased-in-Ice and Ice Glazed Products.”

Unused Dry Tare is all unused packaging materials (including glue, labels, ties, etc.) that contain 

or enclose a product. It includes prizes, gifts, coupons, or decorations that are not part of the 

product. If testing packages in retail store locations where they are packaged, and sold in small 

quantities to the ultimate consumers, the basic test procedure may be modified by using samples of 

the packaging material available in the store. 

Wet Tare is used tare material where no effort is made to dry the tare material. Free-flowing liquids 

are considered part of the tare weight.

Wet tare procedures must not be used to verify the labeled net weight of packages of meat and 

poultry packed at an official United States Department of Agriculture (USDA) facility and bearing 

a USDA seal of inspection. The USDA Food Safety and Inspection Service (FSIS) adopted specific 

sections of the 2005 4th Edition of NIST Handbook 133 by reference in 2008 but not the “wet tare” 

method for determining net weight compliance. FSIS considers the free-flowing liquids in 

packages of meat and poultry products, including single-ingredient, raw poultry products, to be 

integral components of these products (see Federal Register, September 9, 2008 [Volume 73, 

Number 175] [Final Rule – pages 52189-52193]).

If the jurisdiction uses wet tare to determine net weight, follow the procedures described below that 

reference Used Dry Tare, except make no effort to dry the tare material. If Wet Tare is used to 

verify the net weight of the packages, the inspector must allow for moisture loss. 

(Amended 2010)

2.3.5.1. Determination of Tare Sample and Average Tare Weight

Except in the instance of applying Unused Dry Tare, use this procedure for selecting and 

determining the tare sample and average tare weight. Depending upon the initial tare sample 

results, additional tare samples may need to be taken. 

1. Determine the initial tare sample size using Column 5 under initial tare sample size in 

Appendix A. Table 2-1. “Sampling Plans for Category A” or Column 3 under initial tare 

sample size in Appendix A, Table 2-2. “Sampling Plans for Category B.” Record the 
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initial tare sample size in Box 7 on the appropriate form located in Appendix C. Model 

Inspection Report Forms.

Note: The initial tare sample size is considered the total tare sample size for the inspection 

lot when the sample size is less than 12.

2. Except in the instance of applying Unused Dry Tare, select the packages for the initial 

tare sample from the sample packages. Mark the first two (three or five) packages in the 

order the random numbers were selected; these packages are the initial tare sample. 

3. Determine the gross weight of each package and record it in Block a, “Gross Wt,” under 

the headings “Pkg. 1,” “Pkg. 2,” “Pkg. 3,” etc. on the report form.

4. Except for aerosol or other pressurized packages, open the sample packages, empty, 

clean, and dry them as appropriate for the packaging material.

5. Determine the tare weight for each package in the initial tare sample and record the value 

in Block b, “Tare Wt” under the appropriate package number column.

6. For sample sizes of 12 or more, subtract the individual tare weights from the respective 

package gross weights (Block a, minus Block b, on the report form) to obtain the net 

weight for each package and record each value in Block c, “Net Wt,” on the report form.

7. Determine and record the “Range of Package Errors (Rc)” for the initial tare sample in 

Box 9 on the report form. The range is the difference between the package errors.

(Amended 2002)

8. Determine and record the “Range of Tare Weights (Rt)” in Box 10.

9. Compute the ratio Rc/Rt by dividing the value in Box 9 by the value in Box 10. Record 

the resulting value in Box 11. Rc and Rt must both be in the same unit of measure or 

both in dimensionless units.

10. Determine and record in Box 12 the total number of tare samples to be opened for the tare 

determination from either Appendix A, Table 2-3. “Category A” or Table 2-4. “Category B.” 

 In the first column (titled Ratio of Rc/Rt), locate the range in which the computed 

Rc/Rt falls. Then, read across to the column headed with the appropriate sample 

size.

 If the total number of packages to open equals the number already opened, go to 

Step 11.

 If the total number of packages to open is greater than the number of packages 

already opened, compute the number of additional packages to open for the tare 

determination. 

 Open and weigh as per Steps 3, 4, and 5 and go to Step 11. Enter the total number 

of tare samples in Box 12.
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11. Determine the average tare weight using the tare weight values for all the packages 

opened and record the average tare weight in Box 13.

2.3.5.1.1. Unused Dry Tare

The average tare weight may be determined using samples of Unused Dry Tare when testing 

meat, poultry, or any other products that are not subject to regulation of the Food and Drug 

Administration (FDA). You may utilize Unused Dry Tare samples when conducting 

inspections at locations where the point-of-pack and sale are identical (e.g., store-packed 

products in a supermarket meat case). To determine Unused Dry Tare at the point-of-sale, 

randomly select two (2) samples of Unused Dry Tare, and weigh each separately. If there is 

no measurable variation in weight between the samples, proceed with the test using the weight 

of one of the samples. If the weight of the two (2) initial samples varies, randomly select 

three (3) additional tare samples and determine the average weight of all five (5) samples. Use 

this value as the average tare weight.

2.3.5.2. Special Procedures for Determining Tare

Aerosols and Other Pre-Pressurized Containers

Aerosol and other pre-pressurized containers (aerosols) are handled differently for two reasons: 

first, regulations in NIST Handbook 130 under the Uniform Packaging and Labeling Regulation 

(UPLR) require that packages designed “to deliver” the product under pressure, “must state the net 

quantity of the contents that will be expelled when the instructions for use as shown on the container 

are followed.” This means that any product retained in aerosol containers after full dispersion is 

included in the tare weight. Second, aerosol containers must not be opened because they are 

pressurized; for safety reasons they should not be punctured or opened. When emptying aerosol 

containers to determine a tare weight, exhaust them in a well-ventilated area (e.g., under an exhaust 

hood or outdoors) at least 15 m (50 ft) from any source of open flame or spark.

To ensure that the container properly dispenses the product, read and follow any dispensing 

instructions on the package. If shaking during use is specified in the instructions, periodically shake 

(at least two or three times during expulsion of the product). If directions are not given, shake the 

container five times with a brisk wrist twisting motion. If the container has a ball agitator, continue 

the shaking procedure for one minute after the ball has shaken loose.

Vacuum Packed Coffee

The gross weight of a container (typically a metal can) of vacuum-packed coffee will be more after 

the seal is broken and air enters the can. In the procedure to determine the tare weight of the 

packaging material, correct the gross weight determined for unopened cans as follows. Use the 

initial tare sample packages, weigh, and record the gross weight of the product-filled cans before 

and after breaking the vacuum seal. Compute the average gross weight difference (open weight 

minus sealed weight) and record this in Box 13a of the report form. The nominal gross weight

equals the average tare weight minus the average difference in gross weights plus the labeled weight 

(Box 14): Box 13 − Box 13a + Box 1.

(Amended 2002)
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Determine Nominal Gross Weight and Package Error

2.3.6.1. Determine Nominal Gross Weight

A nominal gross weight is used to calculate package errors. To compute the nominal gross weight, 

add the average tare weight (recorded in Box 13) to the labeled weight (recorded in Box 1). Record 

in Box 14.

The nominal gross weight is represented by the formula:

Nominal gross weight = average tare weight + labeled weight

2.3.6.2. Determine Package Error

To obtain the package error, subtract the nominal gross weight from each package’s gross weight. 

The package error is represented by the formula:

Package error = gross weight − nominal gross weight

(Added 2010)

Determine the errors of the packages opened for tare by subtracting the nominal gross weight

recorded in Box 14 from the individual package gross weights recorded for each package (Pkg. 1, 

Pkg. 2, etc.) in Block a, “Gross Wt.” The nominal gross weight must be used, rather than the actual 

net weight, for each package to determine the package error. This ensures that the same average 

tare weight is used to determine the error for every package in the sample, not just the unopened 

packages.

• Standard Packages. – Record the package error in the appropriate plus or minus column 

on the report form for each package opened for tare.

• Random Packages. – Determine the package error for the tare sample using a nominal 

gross weight for each package so that all of the package errors are determined with the 

same tare weight value. Record the package error on the Random Package Report Form 

in the appropriate plus or minus column under Package Errors.

Note: Converting the package error to dimensionless units allows the inspector to record the 

package errors as whole numbers disregarding decimal points and zeroes in front and unit of 

measure after the number. This section does not prohibit the use of software or units of weight 

instead of dimensionless units.

Example: 

If weighing in 0.001 lb increments, the unit of measure is 0.001 lb. If the package error 

for the first package opened for tare is + 0.008 lb, instead of recording 0.008 lb in the plus 

column, record the error as “8” in the plus column. If the second package error is 

+ 0.060 lb, record the package error as “60” in the plus column, and so on. 

Determine the errors for the rest of the sample by subtracting the nominal gross weight (Box 14) 

from the gross weight of each of the unopened sample packages. Record the package errors in the 

“Package Errors” section of the report form using either units of weight (lb or g) or dimensionless 

units.
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2.3.6.3. Compute Total Package Error

Add all the package errors for the packages in the sample. Be sure to subtract the minus package 

errors from the plus package errors and to record the total net error in Box 15, indicating the positive 

or negative value of the error.

(Amended 2010)

Evaluate for Compliance 

This inspection lot will pass or fail based on the sample test results. The following steps lead the 

inspector through the process to determine if a sample passes or fails. If the product is subject a

moisture allowance, follow the procedures under Section 2.3.8. “Moisture Allowances” to correct the 

MAV.

2.3.7.1. Maximum Allowable Variation (MAV) Requirement

1. Compare each minus package error with the MAV recorded in Box 3 or Box 4 (if using 

dimensionless units). Circle the package errors that exceed the MAV. These are 

“Unreasonable Minus Errors.” Record the number of unreasonable minus errors found in 

the sample in Box 16.

2. Compare the number in Box 16 with the number of unreasonable errors allowed (recorded 

in Box 8). If the number found exceeds the allowed number, the lot fails. Record in Box 17 

whether the number of unreasonable errors found is less or more than allowed.

Note: If a total quantity declaration on a multiunit or variety package is being verified, and the 

MAV applied is not based on a percent of the labeled quantity (see Section 1.2.4.1. “Total 

Quantity MAV for Multiunit and Variety Packages).

(Note Added 2022)

2.3.7.2. Average Requirement

1. Determine the average error by dividing the total error recorded in Box 15 by the sample 

size recorded in Box 6. Record the average error in Box 18 if using dimensionless units or 

in Box 19 if using units of weight. 

2. Compute the average error in terms of weight (if working in dimensionless units up to this 

time) by multiplying the average error in dimensionless units by the unit of measure and 

record the value in Box 19. If the average error is positive, the sample passes the average 

requirement. If the average error is negative, the sample fails under a “Category B” test. 

Record in Box 20.

Note: If the total error recorded in Box 15 is a plus value, and Box 17 is “No,” (the number of 

unreasonable errors is equal to or less than the number allowed, recorded in Box 8), the lot 

passes.

(Refer to Section 1.4.1. Net Quantity of Contents Requirements for Pesticides Labeled with 

Minimum Net Quantity of Contents Declarations.”)

3. If the average error is a negative value when testing under the Sampling Plans for 

“Category A,” compute the Sample Error Limit (SEL) as follows:
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 Compute the Sample Standard Deviation and record it in Box 21. 

ss = � 11

nn − 11�(XXii − XX̄ )22

nn

ii=11

 Obtain the Sample Correction Factor from Column 3 of Appendix A. Table 2-1. 

“Sampling Plans for Category A” test. Record this value in Box 22.

 Compute the Sample Error Limit using the formula:

Sample Error Limit (Box 23) =

Sample Standard Deviation (Box 21) × Sample Correction Factor (Box 22)

4. Compliance Evaluation of the Average Error:

 If the value of the Average Error (Box 18) is smaller than the Sample Error Limit 

(Box 23), the sample passes.

 If the value of the Average Error (disregarding the sign) (Box 18) is larger than the 

Sample Error Limit (Box 23), the sample fails. However, if the product is subject to 

moisture loss, the sample does not necessarily fail. Follow the procedures under 

“Moisture Allowances” in this chapter.

(Amended 2018) 

(Amended 2022) 

Moisture Allowances 

When no predetermined allowance is found in NIST Handbook 133, the potential for moisture loss 

must be considered. Inspectors should follow their jurisdiction’s guidance for making their 

determination on an acceptable moisture allowance.

(Added 2010) 

If the product tested is subject to moisture loss, provide for the moisture allowance by following one of

the two procedures listed below.

2.3.8.1. Applying Moisture Loss before Determining Package Errors

1. Determine the percent value of the moisture allowance if the product is listed below. (see 

Table 2-3. “Moisture Allowances.”)
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Table 2-3.

Moisture Allowances

Verifying the labeled net 

weight of packages of:

Moisture 

Allowance is: Notes

Flour 3 %

Dry pet food 3 %

Dry pet food means all extruded dog and cat foods and 

baked treats packaged in Kraft paper bags and/or 

cardboard boxes with a moisture content of 13 % or less at 

time of pack.

Pasta products 3 %

Pasta products means all macaroni, noodle, and like 

products packaged in kraft paper bags, paperboard 

cartons, and/or flexible plastic bags with a moisture 

content of 13 % or less at the time of pack.

Borax see Section

2.4. Borax

Wet Tare Only1

Fresh poultry 3 %

Fresh poultry is defined as poultry above a temperature of 

− 3 °C (26 °F) that yields or gives when pushed with the 

thumb.

Franks or hot dogs 2.5 %

Bacon, fresh sausage, 

and luncheon meats 0 %

For packages of bacon, fresh sausage, and luncheon meats, 

there is no moisture allowance if there is no free-flowing 

liquid or absorbent material in contact with the product 

and the package is cleaned of clinging material. Luncheon 

meats are any cooked sausage product, loaves, jellied 

products, cured products, and any sliced sandwich-style 

meat. This does not include whole hams, briskets, roasts, 

turkeys, or chickens requiring further preparation to be 

made into ready-to-eat sliced product. When there is no 

free-flowing liquid inside the package and there are no 

absorbent materials in contact with the product, Wet Tare 

and Used Dried Tare are equivalent.

1

Wet tare procedures must not be used to verify the labeled net weight of packages of meat and poultry 

packed at an official United States Department of Agriculture (USDA) facility and bearing a USDA seal 

of inspection. The Food Safety and Inspection Service (FSIS) adopted specific sections of the 2005 

4th edition of NIST Handbook 133 by reference in 2008 but not the “Wet Tare” method for determining 

net weight compliance. FSIS considers the free-flowing liquids in packages of meat and poultry 

products, including single-ingredient, raw poultry products, to be integral components of these products 

(see Federal Register, September 9, 2008 [Volume 73, Number 175] [Final Rule – pages 52189-52193]).
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Table 2-3.

Moisture Allowances

Notes:

(1) There is no moisture allowance when inspecting meat and poultry from a USDA inspected plant 

when Used Dry Tare and “Category A” sampling plans are used.

(2) For the Wet Tare Only section of Table 2-3. “Moisture Allowances,” free-flowing liquid and

liquid absorbed by packaging materials in contact with the product are part of the wet tare.

(Note Added 2010)

(Amended 2010 and 2013)

2. To compute moisture allowance, multiply the labeled quantity by the decimal percent value 

of the allowance. Record this value in Box 13a.

Example: 

Labeled net quantity of flour is 907 g (2 lb)

Moisture Allowance is 3 % (0.03)

Moisture Allowance = 907 g (2 lb) × 0.03 = 27 g (0.06 lb)

3. If the Moisture Allowance is known in advance (e.g., flour, pasta products, and dry pet 

food), it can be applied by adjusting the Nominal Gross Weight used to determine the 

sample package errors. The Moisture Allowance in Box 13a is subtracted from the

Nominal Gross Weight to obtain an Adjusted Nominal Gross Weight which is entered in 

Box 14. The Nominal Gross Weight is defined in Section 2.3.6.1. as the sum of the Labeled 

Weight and the Average Tare Weight from Box 13.

Example:

Use a Labeled Weight of 907 g (2 lb) and an Average Tare Weight of 14 g 

(0.03 lb)

The calculation is:

Labeled Net Quantity 907 g (2 lb) + Average Tare Weight 14 g (0.03 lb) = 921 g 

(2.03 lb) – Moisture Allowance 27 g (0.06 lb) = Adjusted Nominal Gross Weight 

of 894 g (1.97 lb)

This result is entered in Box 14.

4. Determine package errors by subtracting the Adjusted Nominal Gross Weight from the 

Gross Weights of the Sample Packages.

Example:

The calculation is:

Gross Weight of the Sample Packages – Adjusted Nominal Gross Weight =

Package Error

Note: When the Nominal Gross Weight is adjusted by subtracting the Moisture Allowance 

value(s) the Maximum Allowable Variation(s) is not changed. This is because the errors that 
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will be found in the sample packages have been adjusted by subtracting the Moisture 

Allowance (e.g., 3 %) from the Nominal Gross Weight. That increases the individual package 

errors by the amount of the moisture allowance (e.g., 3 %). If the value(s) of the MAV(s) were 

also adjusted it would result in doubling the allowance. MAV is always based on the labeled 

net quantity.

(Added 2010)

2.3.8.2. Applying Moisture Allowance after Determining Package Errors

Adjustments can be made when the value of the Moisture Allowance is determined following the 

test (e.g., after the sample fails or if a packer provides reasonable moisture allowance based on data 

obtained using a scientific method) using the following approach:

If the sample fails the Average Requirement but has no unreasonable package errors, only Step 1 

is used. If the sample passes the Average Requirement but fails because the sample included one 

or more Unreasonable Minus Errors, only Step 2 is used.

If the sample fails the Average and MAV Requirements, both of the following steps are applied.

1. Use the following approach to apply a Moisture Allowance to the Average Requirement

after the test is completed: 

 the Moisture Allowance is computed;

Example: 

3 % × 907 g (2 lb) = 27 g (0.06 lb) 

 added to the Sample Error Limit;

Example: 

If the Sample Error Limit is 0.023, add 0.06 to obtain an Adjusted Sample 

Error Limit of 0.083)

 the Adjusted Sample Error Limit is then compared to the Average Error of the Sample;

and

 if the average error (disregarding sign) in Box 18 is smaller than the Adjusted Sample 

Error Limit, the sample passes.

HOWEVER,

 if the average error (disregarding sign) in Box 18 is larger than the Adjusted Sample 

Error Limit, the sample fails.

2. To apply Moisture Allowance to the MAV(s) after the test, the following method is 

recommended:

 compute Moisture Allowance;

Example: 

3 % × 907 g (2 lb) = 27 g (0.06 lb)
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 add to MAV for labeled net quantity of the package to get Adjusted Maximum 

Allowable Variations;

Example:

MAV for 907 g (2 lb) is 31.7 g (0.07 lb) + 27 g (0.06 lb) =

Adjusted Maximum Allowable Variation(s) of 58.7 g (0.13 lb)

 compare each minus package error to the Adjusted MAV;

 mark package errors that exceed the Adjusted MAV and record the number of 

unreasonable minus errors found in the sample; and

 if this number exceeds the number of unreasonable errors allowed, the sample fails.

(Added 2010)

2.3.8.3. Moisture Allowance Gray Area

When the average error of a lot of fresh poultry, franks/hot dogs, or pasta products is minus but 

does not exceed the established “moisture allowance” or “gray area,” contact the packer or plant

management personnel to determine what information is available on the lot in question. Questions 

to the plant management representative may include:

• Is a quality control program in place?

• What information is available concerning the lot in question?

• If net weight checks were completed, what were the results of those checks?

• What adjustments, if any, were made to the target weight?

Note: If the plant management has data on the lot, such data may help to substantiate that the “lot” 

had met the net content requirements at the point of manufacture.

This handbook provides “moisture allowances” for some meat and poultry products, flour, pasta 

products, and dry pet food. These allowances are based on the premise that when the average net 

weight of a sample is found to be less than the labeled weight, but not by an amount that exceeds 

the allowable limit, either the lot is declared to be within the moisture allowance or further 

investigation can be conducted.

Reasonable variations from net quantity of contents caused by the loss or gain of moisture from the 

package are permitted when caused by ordinary and customary exposure to conditions that occur 

under good distribution practices. If evidence is obtained and documented to prove that the lot was 

shipped from the packaging plant in a short-weight condition or was distributed under inappropriate 

or damaging distribution practices, appropriate enforcement action should be taken.

(Amended 2010 and 2013)

2.4. Borax

This audit test is only used if the sample fails a net weight test. This procedure applies to packages of 
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powdered or granular products consisting predominantly (more than 50 %) of borax. This method is used 

to identify possible short-filling by weight at point-of-pack for borax. Since the density of borax can vary 

at point-of-pack, further investigation is required to determine whether such short-filling has occurred. Use 

the following procedure to determine if packages of borax are labeled correctly. Borax shall be labeled by 

weight. Borax can lose more than 23 % of its weight due to moisture loss. However, it does not lose 

volume with moisture loss, and this property makes possible a method of volume testing based on a density 

determination in the event that the net weight of the borax does not meet the average or individual package 

requirements. 

(Amended 2016)

Test Equipment

• Dry measure with a capacity of 550.6 mL or (1 dry pt), 1101 mL (dry quart), 1000 mL (liter)

• Metal funnel with slide-gate and stand

• A scale that meets the requirements in Chapter 2, Section 2.2. “Measurement Standards and 

Test Equipment.”

• Straightedge or ruler

• Safety glasses

• Gloves

• Dust mask

• Level (at least 15 cm [6 in] in length)

• Pan or drop cloth/polyethylene sheeting for catching overflow of dry measure

• Borax Audit Worksheet

(Amended 2016)

Test Procedure

Use this procedure only if the sample fails to meet the package requirements in Section 2.3.7. “Evaluate 

for Compliance.”

1. Select the package with the lightest gross weight. Fill out Boxes 1 through 3 of the Borax 

Audit Worksheet.

2. Record the volume declared on the package (Box 4). This volume declaration shall not appear 

on the principal display panel. Instead, it shall appear on the back, side, or bottom of the 

package and may read as:

Volume _________ mL per NIST Handbook 133

Note: 1 mL = 1 cm3

3. Determine the gross weight of the package (Box 5).
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4. Look up the dry measure used in the following table and record the volume (Box 8).

Dry Measure Volume in Milliliters

Dry Pint 550.6 ml

Dry Quart 1101 ml

Liter 1000 ml

5. Determine the empty weight of dry measure and record the value (Box 9.)

(a) Place the dry measure in the pan or on top of drop cloth/polyethylene sheeting and verify 

that it is level. Place the funnel on top of the dry measure and close the funnel side gate.

(b) Pour an adequate amount of borax into the funnel so that the dry measure will be filled to 

overflowing.

(c) Quickly remove the slide-gate from the funnel, allowing the borax to flow into the dry 

measure. To ensure that the borax is free-flowing, repeat Steps 5 (a), (b), and (c) at least 

three times. After the final filling, go to Step 5 (d).

(d) Carefully, without agitating the dry measure, remove the funnel and level off the borax 

with the straightedge or ruler at a right angle to the rim of the cup, and carefully draw it 

across the top of the dry measure to leave an even surface. If the surface of the borax is 

not smooth, repeat Steps 5 (a), (b), (c), and (d). If the surface of the borax is smooth, 

proceed to Step 6.

6. Determine the gross weight of the filled dry measure and borax (Box 10).

7. Subtract the empty weight of the dry measure from the gross weight of the dry measure 

(Box 10 – Box 9) to obtain the net weight of the borax in the dry measure (Box 11).

8. Determine the tare weight of the package (Box 6).

9. Determine the net weight of package (Box 7).

10. Determine the net volume of the borax by dividing the net weight of the package (Box 7) by 

the net weight of the borax in the dry measure (Box 11) and multiply the result by the volume 

of the dry measure (Box 8). The result is the net volume of the borax in the package in 

milliliters (Box 12).

If the net volume of borax in the lightest package equals or exceeds the declared volume on the 

package, treat the lot as being in compliance based on volume and take no further action. If 

the net volume of borax in the lightest package is less than the declared volume on the package, 

further compliance testing will be necessary. 

11. Take further steps to determine if the lot was in compliance with net weight requirements at 

point-of-pack or was short-filled by weight. To determine this, perform a laboratory moisture 

loss analysis to ascertain the weight of the original borax when it was fully hydrated; obtain 

additional data at the location of the packager; and/or investigate the problem with the packager 

of the borax.

(Amended 2016)
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2.5. Determination of Drained Weight

Since the weight per unit volume of a drained product is of the same order of magnitude as that of the 

packaging liquid that is drained off, an “average nominal gross weight” cannot be used in checking 

packages of this type. The entire sample must be opened. The procedure is based upon a test method 

accepted by the U.S. Food and Drug Administration (FDA).

A tare sample is not needed because all the packages in the sample will be opened and measured.

The weight of the container plus drained-away liquid is determined. This weight is then subtracted from 

the gross weight to determine the package error.

Test Equipment

• Scales and weights recommended in Section 2.2. “Measurement Standards and Test 

Equipment” are suitable for the determination of drained weight.

• Sieves

 For drained weight of 1.36 kg or (3 lb) or less, one 203 mm or (8 in) No. 8 mesh U.S. 

Standard Series sieve, receiving pan, and cover;

 For drained weight greater than 1.36 kg or (3 lb), one 304 mm or (12 in) sieve, with same 

specifications as above;

 For canned tomatoes, a U.S. Standard test sieve with 11.2 mm (7/16 in) openings must be 

used. 

Note: The sieve is used, if it is necessary, to determine the percentage of solids in the container.

• Stopwatch

(Amended 2010)

Test Procedure

1. Follow Sections 2.3.1 through Section 2.3.4. to define an inspection lot, select “Category A” or 

a “Category B” sampling plan in the inspection (depending on the location of test); and select a 

random sample.

2. Use Appendix C. “Standard Package Report.” Fill out Boxes 1 through 8. Determine and 

record on a worksheet the weight of the receiving pan.

3. Determine and record on a worksheet the gross weight of each individual package comprising 

the sample.

4. Pour the contents of the first package into the dry sieve with the receiving pan beneath it, incline 

sieve to an angle between 17° to 20° from horizontal to facilitate drainage, and allow the liquid 

from the product to drain into receiving pan for two minutes. (Do not shake or shift material on 

the sieve.) Remove sieve and product.
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5. Weigh the receiving pan, liquid, wet container, and any other tare material. (Do not include 

sieve and product.) Record this weight as tare and receiving pan on the worksheet.

6. Subtract the weight of the receiving pan, determined in Step 2, from the weight obtained in 

Step 5 to obtain the package tare weight (which includes the weight of the liquid). Record 

package tare weight on the worksheet with the associated gross weight of the package.

7. Subtract the tare weight, found in Step 6, from the corresponding package gross weight 

determined in Step 3 to obtain the drained weight of that package. Record package net weight

on the worksheet. Determine the package error (drained weight – labeled drained weight) and 

record on worksheet.

8. Repeat Steps 4 through 7 for the remaining packages in the sample after cleaning and drying the 

sieve and receiving pan between measurements of individual packages.

9. Transfer the individual package errors to the Standard Pack Report form.

10. To determine lot conformance, return to Section 2.3.7. “Evaluate for Compliance.”

2.6. Net Weight of Encased-in-Ice and Ice Glazed Products

Net Weight of Encased-in-Ice and Frozen Block Product 

Note: For determining the net weight of ice glazed seafood, meat, poultry, or similar products, follow 

the procedure in Section 2.6.2. “Net Weight of Ice Glazed Seafood, Meat, Poultry or Similar Products.” 

2.6.1.1. Test Equipment

• Balance and weights (used to verify accuracy) 

• Partial immersion thermometer or equivalent with 1 °C (2 °F) graduations and a − 35 °C 

to + 50 °C (− 30 °F to +120 °F) accurate to ± 1 °C (± 2 °F)

• Water source and hose with an approximate flow rate of 4 L to 15 L (1 gal to 4 gal) per 

minute for thawing blocks and other products 

• Sink or other receptacle [i.e., bucket with a capacity of approximately 15 L (4 gal)] for 

thawing blocks and other products

• A wire mesh basket (e.g., used for testing large frozen blocks of shrimp) or a container that 

is large enough to hold the contents of one package (e.g., 2.27 kg or [5 lb] box of shrimp) 

and has openings small enough to retain all pieces of the product (e.g., an expanded metal 

test tube basket lined with standard 16-mesh screen)

• Number 8 mesh, 203 mm (8 in) or 304 mm (12 in) sieve

• Means to determine a 30° angle 

• Pan for weighing the thawed and drained product 
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• Stopwatch

• Ice Glazed Package Worksheet (see Appendix C. “Model Inspection Report Forms”)

• Ice Glazed Package Report (see Appendix C. “Model Inspection Report Forms”)

2.6.1.2. Test Procedure for Encased-in-Ice Product Only

1. Follow Sections 2.3.1. through 2.3.4. to define the inspection lot, select a sampling plan 

and select a random sample.

2. Place the unwrapped frozen seafood, meat, poultry, or similar products in the wire mesh 

basket or an open container to thaw (e.g., it is not placed in a plastic bag) and immerse in 

a 15 L (4 gal) or larger container of fresh water at a temperature between 23 °C to 29 °C 

(75 °F to 85 °F). Submerge the basket so that the top of the basket extends above the water 

level. 

3. Maintain a continuous flow of water into the bottom of the container to keep the 

temperature within the specified range. This is accomplished by maintaining a constant 

flow of warm water into the container holding the product (e.g., place a bucket in a sink to 

catch the overflow, and feed warm water into the bottom of the bucket through a hose). 

Note: Direct immersion does not result in the product absorbing moisture because the freezing 

process causes the tissue to lose its ability to hold water.

4. As soon as the product thaws, determined by loss of rigidity, transfer all material to a sieve 

(203 mm [8 in] for packages 453 g [1 lb] or less). A sieve 304 mm [12 in] for packages 

weighing more than 453 g [1 lb]) and distribute it evenly over the sieve.

5. Without shifting the product, incline the sieve 30° from the horizontal position to facilitate 

drainage, and drain for two minutes.

6. While the product is draining, place pan on scale and tare the scale reading to zero.

7. At the end of the drain time, immediately transfer the product to the tared pan for weighing 

to determine the net weight of the product.

(Amended 2010)

Net Weight of Ice Glazed Seafood, Meat, Poultry or Similar Products

For ice glazed seafood, meat, poultry or similar products, determine the net weight after removing the 

glaze using the following procedure. 

2.6.2.1. Test Equipment

• Balance and weights (used to verify accuracy)

• Continuous cold water source 

• Number 8 sieve and receiving pan, 203 mm (8 in) for packages 453 g (1 lb) or less. A 

304 mm (12 in) for packages more than 453 g (1 lb).
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• Means to determine a 17° to 20° angle

• Stopwatch

2.6.2.2. Test Procedures for Ice Glazed Product Only

1. Follow Sections 2.3.1. through Section 2.3.4. to define an inspection lot, select 

“Category A” or a “Category B” sampling plan in the inspection (depending on the location 

of test), and select a random sample.

2. Fill out the header information on boxes 1 through 8 on the Ice Glazed Package Report 

form. A tare sample is not needed. Record package price, price per pound, lot size, sample 

size, and unit of measure in Step 1 of the Ice Glazed Package Worksheet. (see Appendix C. 

“Model Inspection Report Forms.”)

Note: Use an official inspection report to record the inspection information. Attach additional 

worksheets, test notes, and other information as needed. This handbook provides an Ice Glazed 

Package Worksheet and Ice Glazed Package Report form in Appendix C. “Model Inspection 

Report Forms.” Modify the worksheet, package report and the box numbers to meet your 

agency’s needs. Other formats that contain more or less information may be acceptable.

3. Number each package. Weigh each package for gross package weight and enter in Row 1 

“Gross Pkg. Weight” on the Ice Glazed Worksheet.

4. Enter the labeled net weight in Row 2 “Labeled Net Weight” for each package on the 

worksheet. If dual units, determine and enter the larger of the two units.

5. Record the maximum allowable variation on Row 3 “MAV” on the worksheet.

6. Weigh receiving pan and record the weight in Row 4, “Receiving Pan Weight” on the 

worksheet.

7. Deglaze the product. Remove a package from low temperature storage; open it immediately 

and place the contents in the sieve or other draining device (e.g., colander) under a gentle 

spray of cold water. Carefully agitate the product. Handle with care to avoid breaking the 

product. Continue the spraying process until all ice glaze, that is seen or felt is removed. 

In general, the product should remain rigid; however, the ice glaze on certain products, 

usually smaller sized commodities, sometimes cannot be removed without partial thawing 

of the product. Nonetheless, remove all ice glaze because it may be a substantial part of the 

package weight.

8. Transfer the product to the sieve (if the product is not already in the sieve). Without shifting 

the product, incline the sieve to an angle of 17° to 20° to facilitate drainage and drain (into

waste receptacle or sink) for two minutes using a stopwatch.

9. At the end of the drain time, immediately transfer the entire product to the receiving pan for 

weighing to determine the net weight. 
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10. Place the product and receiving pan on the scale and weigh. Record the net weight in Row 5 

on the ice glazed package worksheet. The net weight of product is equal to the weight of 

the receiving pan and the product minus the receiving pan weight.

11. The package error is equal to the net weight of the product minus the labeled weight. Record 

the package error in Row 6.

12. Repeat Steps 2 through 10 for each package in the sample, cleaning the sieve, cleaning and 

drying the receiving pan between package measurements.

13. Transfer data from the Ice Glazed Package Worksheet to the Ice Glazed Package Report.

Evaluation of Results

Follow the procedures in Section 2.3.7. “Evaluate for Compliance.”

(Amended 2010)

2.7. Determining the Net Weight and Percentage of Purge in Packages of Fresh and 

Frozen Chitterlings

Test Equipment

• Scale or balance and mass standards (The standards are used to verify the accuracy and 

repeatability of the weighing device.)

• Partial immersion thermometer or equivalent with 1 °C (2 °F) graduations and a − 35 °C to 

+ 50 °C (− 30 °F to + 120 °F) accurate to ± 1 °C (± 2 °F) 

• Sink (e.g., water bath, ice chest) or other receptacle of suitable size to hold the packages for 

thawing, water source, and hose with fresh water that can be maintained at a temperature 

between 23 °C to 29 °C (75 °F to 85 °F) (used for thawing plastic bags or buckets of 

chitterlings)

An alternative thawing procedure for packages requires access to a refrigerator that must be 

available for storing sample packages for several days to thaw. 

• Stainless Steel Sieve(s) and Drain Pan(s) with number 8 mesh, 203 mm (8 in) or 304 mm (12 in) 

(The use is based on the labeled net weight of the package under inspection.)

• Chitterlings Worksheet for Category A and Category B (see Appendix C. “Model Inspection 

Report Forms.”) 

• Stopwatch (to measure drain periods)

• Knife or box cutter (to open packages)

• Waterproof marking pen (for numbering the packages)

• Disposable (non-latex) gloves

• Paper towels (drying sieve drain pan, packages and work area)
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• Large plastic bags (to hold product emptied from packages)

• Plastic rod (to insert into buckets of chitterlings to determine if the product is thawed and to 

ensure there are no chunks of ice remaining). 

(Added 2015)

Test Procedure for Net Weight and Purge Determination for Fresh and Frozen 

Chitterlings.

This procedure is used to determine (1) the net weight and (2) the purge in packages of fresh and frozen 

chitterlings. The purge determination procedure requires the destructive testing of all the sample 

packages.

1. Follow Sections 2.3.1. “Define the Inspection Lot,” 2.3.2. “Select Sampling Plans” (use the 

“Category A” Sampling Plans in Appendix A. “Tables,” Table 2-1. “Sampling Plans for 

Category A” if the testing is outside of a USDA inspected packing facility, or the “Category 

B” Sampling Plan in Table 2-2. “Sampling Plans for Category B” if the testing is inside a 

USDA inspected packing facility), 2.3.3. “Record Inspection Data,” and 2.3.4. “Random 

Sample Selection.” 

2. Select the random sample of packages. 

3. Dry the sample packages and number each (e.g., 1 to 12) using a waterproof marker. 

4. Record the Product Brand, Inspector Name, Labeled Net Weight (top of Column A), Packer 

Identity, Lot Code, Number of Unreasonable Errors, MAV from Appendix A. “Tables,” 

Table 2-9. “U.S. Department of Agriculture, Meat, Poultry, and Siluriformes Groups and 

Lower Limits for Individual Packages (Maximum Allowable Variations [MAVs]”), and the 

Unit of Measure of the scale used for weight determinations on the Chitterlings Worksheet

(Appendix C. “Model Inspection Report Forms”). The appropriate information can be 

transferred to an official inspection report at the conclusion of the inspection. The worksheet 

should be added to the official record of the inspection.

(Added 2015)

2.7.2.1. Net Weight and Purge Determinations 

Follow these procedures to determine the net weight and amount of purge from chitterlings. 

2.7.2.1.1. Test Procedure for Determining the Net Weight and Purge from Fresh and 

Frozen Chitterlings 

1. Determine the Gross Weight of each sample package (record in Column B). 

2. Determine the tare weight of the sieve drain pan (record in Drain Pan Tare above 

Column F). 

Frozen Chitterlings

3. Fully immerse the unopened package of frozen chitterlings in a water bath maintained 

at a temperature between 23 °C to 29 °C (75 °F to 85 °F). 
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Notes: 

(1) An alternative approach to thawing large frozen packages (e.g., 5 kg [10 lb] 

plastic pails) is to randomly select (mark them to be held for inspection) the 

sample packages and place them in a refrigerator for partial thawing over 

several days, and then carrying out the final thawing using the water bath 

technique.

(2) If the products are to be placed in refrigerated storage for several days for 

partial thawing, segregate them from other product inventory and mark each 

container with an identifier to allow the inspector to ensure that they were 

the samples selected for testing (mark both lid and container on buckets) 

when the inspection is resumed after the thawing process. Also, mark the 

packages with a conspicuous notice that they are being held for inspection.

4. Maintain a continuous flow of water into the bath to keep the temperature within the 

specified range until the chitterlings are thawed. The chitterlings are thawed when it 

is determined by touch that they are not rigid and no ice crystals are observed or felt 

within or on their outside surface. 

Note: For buckets, insert a plastic rod into the chitterlings to determine if the product 

is thawed and to ensure there are no chunks of ice remaining. 

Fresh and Frozen Chitterlings 

5. Draining the Chitterlings – Depending on the availability of a sink, work space, and 

the inspector’s preference, use the procedures in either Method A or Method B to drain 

the chitterlings. Refer to the Table 2-4. “Sieve Size Based on Labeled Net Weight” for 

the appropriate size sieve to use based on the labeled net weight on the package. 

Table 2-4. 

Sieve Size Based on Labeled Net Weight

Labeled Net Weight

Sieve

Diameter

30 Degree Tilt from 

Horizontal Incline Height

If more than 453 g (1 lb) use a: 304 mm

(12 in) 175 mm (6.9 in)

If less than 453 g (1 lb) use a: 203 mm 

(8 in) 116.8 mm (4.6 in)

• This procedure requires that the sieve and drain pan be cleaned and dried after each use. It is a 

good measurement practice to obtain the dry weights of both the sieve and pan and recheck those 

weights periodically during the test to make sure the cleaning and drying procedures are efficient. 

• If the amount of chitterlings in the package exceeds the capacity of the sieve, divide the solids 

evenly among two or more sieves of the same dimensions or make multiple determinations using a 

single sieve. Exercise care when transferring the chitterlings into the sieves to avoid spilling liquid 

which can void the test.

Incline Height
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Method A: Place a sieve over a sink or waste collection container. Pour the chitterlings into 

the sieve and distribute them over the surface of the sieve with a minimum of handling. Hold 

the sieve firmly and incline it 30 degrees (see Figure 2-3. “Sieve with Tilt Block Set at 30 

Degrees” for an example of a tilt block for use with a sink drain set at 30 degrees) to facilitate 

drainage, then start the stop watch and drain for exactly two minutes. At the end of the drain 

time, immediately transfer the chitterlings to a drain pan for weighing. Determine the purged 

net weight of the chitterlings using the following formula and record in Column F of the 

worksheet. 

Drained Chitterlings and Drain Pan – Drain Pan Tare = Purged Net Weight

Method B: Place a sieve on its drain pan. Pour the chitterlings into the sieve and distribute 

them over the surface of the sieve with a minimum of handling. Hold the sieve firmly and 

incline it 30 degrees to facilitate drainage, then start the stop watch and drain for exactly two

minutes. At the end of the drain time, immediately transfer the drain pan with the purged liquid

to the scale for weighing. Dry the empty package to determine its tare weight and enter it in 

Column C. Determine the purged net weight of the chitterlings using the following formula 

and record in Column F of the worksheet. 

(Gross Weight of Package − Package Tare Weight) – (Weight of Purged Liquid & Drain 

Pan − Drain Pan Tare) = Purged Net Weight

(Column B – Column C) − (Weight of Purged Liquid & Drain Pan – Drain Pan Tare) =

Purged Net Weight

6. Calculate Purge using the formula shown below (use the labeled net weight in Column 

A and NOT the gross weight of the package in Column B) and record the result in 

Column G of the Worksheet.

Purge in % = (Labeled Weight − Purged Net Weight) ÷ Labeled Weight × 100

Purge in % = Column A – Column F ÷ Column A × 100

Example: 

The labeled net weight is 5 lb and the Purged Net Weight is 4.19 lb

5 lb – 4.19 lb = 0.81 lb ÷ 5 lb = 0.162 × 100 % = 16.2 % purge

7. Dry the empty package and determine its tare weight (record in Column C of the 

worksheet.) 

Figure 2-3. Sieve with Tilt Block Set at 

30 Degrees.
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8. Subtract the individual Package Tare Weight from the individual Package Gross 

Weight to obtain the Actual Package Net Weight (record in Column D of worksheet). 

Do not use an Average Tare Weight. Use the formula: 

Actual Package Net Weight = Gross Weight − Tare Weight

Actual Package Net Weight = Column B – Column C

9. Subtract the Actual Package Net Weight from the Labeled Net Weight (record in 

Column E of worksheet). Use the formula: 

Package Error = Labeled Net Weight – Actual Package Net Weight

Package Error = Column A – Column D

10. Repeat for all packages in the sample. 

Note: The determination of compliance with the net weight and purge requirements are 

carried out concurrently. The calculation of the average net weight and average purge is 

completed after all of the packages are opened and all purge amounts are obtained. The 

sample must pass both the net weight and purge tests to comply with this section.

(Added 2015)

Evaluations of Results – Compliance Determinations 

1. Net Weight

If there are negative package errors, determine if any of the values exceed the Maximum Allowable 

Variation (MAV) for the packaged quantity in NIST Handbook 133, Appendix A. “Tables,”

Table 2-9. “U.S. Department of Agriculture, Meat, Poultry, and Siluriformes Groups and Lower 

Limits for Individual Packages” (i.e., if the labeled net weight is more than 3 lb up to 10 lb then the 

MAV = 42.5 g [0.094 lb] 1.5 oz). 

 If a package error exceeds the MAV, mark it as “Failed” in the MAV Fail column. 

 Count the number of packages that exceed the MAV. If the number of packages that 

exceed the MAV is greater than the number allowed in NIST Handbook 133, Appendix A. 

“Tables,” Table 2-1. “Sampling Plans for Category A” or Table 2-2. “Sampling Plans for 

Category B," the sample fails. Mark the sample as “Failed” in the Net Weight Compliance 

section of the worksheet. 

 If the sample passes the Individual Package Requirement, apply the Average Error 

Requirement.

Sum the package errors in Column E and enter the value in E1 – Total Error. Divide the value in 

E1 by the Sample Size (n) to obtain an Average Error and enter the value in E2. If the Average 

Error (E2) is a positive number, the sample passes. Go to the Net Weight Compliance Section and 

mark the sample as “Passed.” 
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 If the Average Error (E2) is a negative number, calculate the sample standard deviation of 

the package errors (Column E) and enter it in the block provided in the Net Weight 

Compliance section. 

 Use the Sample Correction Factor (SCF) to calculate the Sample Error Limit (SEL). 

Sample Error Limit (SEL) =

Sample Standard Deviation × Sample Correction Factor

 Disregarding the signs, 

o if the Average Error (E2) is larger than the SEL, the sample fails. Mark it “Failed” 

in the Net Weight Compliance Section of the worksheet, 

or 

o if the Average Error is less than the SEL, the sample passes. Go to the Net Weight 

Compliance Section and mark the sample as “Passed.” 

Note: If a total quantity declaration on a multiunit or variety package is being verified, and the 

MAV applied is not based on a percent of the labeled quantity (see Section 1.2.4.1. “Total Quantity 

MAV for Multiunit and Variety Packages).

(Note Added 2022)

2. Purge 

Follow these procedures to determine the amount of purge from the chitterlings. Apply the Average 

Requirement in Section 2.3.7.2. “Average Requirement” to the purge to determine if the sample 

passes or fails the requirement. The Average Adjusted Purge (AAP) for the sample shall not exceed 

20 % of the labeled weight. The Maximum Allowable Variations (Lower Limits for Individual 

Packages) in NIST Handbook 133, Appendix A. “Tables,” Table 2-9. “U.S. Department of 

Agriculture, Meat, Poultry, and Siluriformes Groups and Lower Limits for Individual Packages 

(Maximum Allowable Variations [MAVs]) are not applied in the purge test. 

 Sum the purge values in Column G and enter the value in G1 – Total Purge. Divide the value 

in G1 by the Sample Size (n) to obtain an Average Purge and enter the value in G2. If the 

Average Purge (G2) is less than or equal to 20 %, the sample passes. Go to the Purge 

Compliance Section and mark the sample as “Passed.” 

 If the Average Purge is greater than 20 %, calculate the Sample Standard Deviation of the 

values in Column G and enter it in the block provided in the Purge Compliance section. 

 Use the Sample Correction Factor (SCF) to calculate the Purge Sample Error Limit (PSEL) in 

percent. 

 Subtract the PSEL from the Average Purge (G2) to obtain an Adjusted Average Purge (AAP) 

and enter that value in G3. 

 Pass or Fail
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o If the AAP (G3) is greater than 20 %, the sample fails. Enter the Purge Value (G3) in 

the Purge Compliance section and mark the sample as “Failed.” 

or 

o if the AAP (G3) is 20 % or less, the sample passes. Enter the Purge Value (G3) in the 

Purge Compliance section and mark the sample as “Passed.” 

(Added 2015) (Amended 2022) 
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