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United States Consumer 

Standards for Potatoes

Effective December 8, 1947

Reprinted December 13, 2018
This is a reprint of the United States Consumer Standards for Potatoes which have 

been in effect since December 8, 1947 and were updated to modify the format.

Voluntary U.S. grade standards are issued under the authority of the Agricultural 

Marketing Act of 1946, which provides for the development of official U.S. grades to 

designate different levels of quality. These grade standards are available for use by 

producers, suppliers, buyers, and consumers. As in the case of other standards for 

grades of fresh and processed fruits, vegetables, and specialty crops these 

standards are designed to facilitate orderly marketing by providing a convenient 

basis for buying and selling, for establishing quality control programs, and for 

determining loan values. 

The U.S. grade standards and inspection instructions for all fresh and processed fruits,

vegetables, and specialty crops are available on the internet and upon request at the 

address below. These documents provide detailed interpretations of the grade standards 

and provide step-by-step procedures for grading the product. 

Grade standards are issued by the U.S. Department of Agriculture (USDA) after careful 

consideration of all data and views submitted during rulemaking. The Department 

welcomes suggestions for improving the standards in future revisions. Comments may be 

submitted to, and copies of standards and inspection instructions obtained from: 

Director, Specialty Crops Inspection Division

Specialty Crops Program, 

USDA, Agricultural Marketing Service

1400 Independence Avenue, SW, STOP 0240 

Washington, D.C. 20250

Authority: 7 U.S.C. 1621-1627. 

Note: Compliance with the provisions of these standards shall not excuse failure to 

comply with the provisions of the Federal Food, Drug, and Cosmetic Act, or 

with applicable State laws and regulations.

Non-Discrimination Policy: In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and 

policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from 

discriminating based on race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, 

marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil 

rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing 

deadlines vary by program or incident.

Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American 

Sign Language, etc.) should contact the responsible Agency or USDA's TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA 

through the Federal Relay Service at (800) 877-8339. Additionally, program information may be made available in languages other than English.

To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a 

Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information 

requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail:

U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-

9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.

USDA is an equal opportunity provider, employer, and lender.
United States Consumer Standards for Potatoes (December 8, 1947)

1

United States Consumer Standards for Potatoes

______________________________________________________________________

Section Page No.

Grades............................................................................................................................ 2

§51.1575 U.S. Grade A Small; U.S. Grade A Medium; U.S Grade A Medium to Large; 

U.S. Grade A Large......................................................................................................... 2

§51.1576 U.S. Grade B Small; U.S. Grade B Medium; U.S. Grade B Medium to Large; 

U.S. Grade B Large......................................................................................................... 2

Size................................................................................................................................. 2

§51.1577 Size range requirements. ............................................................................... 2

Off-Grade ....................................................................................................................... 3

§51.1578 Off- Grade potatoes........................................................................................ 3

Application of Tolerances ............................................................................................ 3

§51.1579 Application of tolerance to individual containers............................................. 3

Definitions...................................................................................................................... 3

§51.1580 Fairly well shaped........................................................................................... 3

§51.1581 Fairly clean..................................................................................................... 4

§51.1582 Soft rot or wet breakdown............................................................................... 4

§51.1583 Damage.......................................................................................................... 4

§51.1584 Internal discoloration. ..................................................................................... 5

§51.1585 Mature. ........................................................................................................... 5

§51.1586 Serious damage. ............................................................................................ 5

§51.1587 Diameter......................................................................................................... 6
United States Consumer Standards for Potatoes (December 8, 1947)

2

Grades

§51.1575 U.S. Grade A Small; U.S. Grade A Medium; U.S Grade A Medium to 

Large; U.S. Grade A Large.

Potatoes of each of these grades shall be of one variety or similar varietal 

characteristics which are fairly well shaped, fairly clean, free from freezing injury, 

blackheart, late blight, and soft rot or wet breakdown, and from damage caused by 

sunburn, second growth, growth cracks, air cracks, hollowheart, internal discoloration, 

cuts, shriveling, sprouting, scab, dry rot, rhizoctonia, other diseases, wireworm, other 

insects, or mechanical or other means. Potatoes of these grades shall also be mature: 

Provided, That potatoes which are not mature and the outer skin loosens or “feathers” 

readily under the usual handling practices need not meet this requirement if they are 

firm and are further designated as “Early” in connection with the grade, as for example 

“U.S. Grade A Medium-Early.” Potatoes on the shown face shall be reasonably 

representative in size and quality of the contents of the containers. (See §51.1577.)

(a) Tolerances. Incident to proper grading and handling, except for the tolerances 

for size, not more than a total of 5 percent, by weight, of the potatoes in any lot 

may fail to meet the requirements of the grade, including not more than 1 percent 

for potatoes affected by soft rot or wet breaking down. (See §51.1579.)

§51.1576 U.S. Grade B Small; U.S. Grade B Medium; U.S. Grade B Medium to 

Large; U.S. Grade B Large.

Potatoes of each of these grades shall meet the requirements for U.S. Grade A Small; 

U.S. Grade A Medium; U.S Grade A Medium to Large; and U.S. Grade A Large, except 

for the increased tolerance for defects specified below. (See §51.1577.)

(a) Tolerances. Incident to proper grading and handling, except for the tolerance for 

size, not more than a total of 20 percent, by weight, of the potatoes in any lot 

may fail to meet the requirements of the grade, but not more than 5 percent shall 

be allowed for potatoes which are seriously damaged by any cause, including not 

more than 1 percent for potatoes affected by soft rot or wet breakdown. (See 

§51.1579.)

Size

§51.1577 Size range requirements.

In addition to the quality requirements specified for the above grades, potatoes shall 

also meet the requirements for minimum and maximum diameter or weight, and the 

tolerances as specified for the various grades in the table appearing in this section. 

Potatoes specified as meeting one for the grades may be of any size within its size 

range requirements, except that it is not permissible to specify a lot as “U.S. Grade A 

Medium to Large,” or “U.S. Grade B Medium to Large,” unless more than 15 percent, by 

weight, of the potatoes are larger than the maximum size required for U.S. Grade A 

Medium, or U.S. Grade B Medium, respectively. For example, a lot of round or 
United States Consumer Standards for Potatoes (December 8, 1947)

3

intermediate-shaped potatoes to be specified as “U.S. Grade A Medium to Large” must 

have more than 15 percent, by weight, of potatoes from 3 to 4 inches in diameter.

Grades

Size range 

requirements, round 

or intermediate 

shaped varieties

Size range 

requirements, long 

varieties

Tolerances for size

Minimum 

diameter 

(Inches)

Maximum 

diameter 

(Inches)

Minimum 

diam. or 

wt.

Maximum 

weight 

(Ounces)

Undersize 

(Percent)

Oversize 

(Percent)

U.S. Grades A & B small 1 1⁄2 2 1⁄4 1 1⁄2 inches 4 3 15

U.S. Grades A & B medium 2 1⁄4 3 4 ounces 10 5 15

U.S. Grades A & B medium to 

large 2 1⁄4 4 4 ounces 16 5 15

U.S. Grades A & B large 3 4 10 ounces 16 5 15

Off-Grade

§51.1578 Off- Grade potatoes.

Potatoes which fail to meet the requirements of any of the foregoing grades shall be OffGrade potatoes.

Application of Tolerances

§51.1579 Application of tolerances to individual containers.

(a) Based on sample inspection, the contents of individual containers in the lot are 

subject to the following limitations: Provided, That the averages for the entire lot 

are within the tolerances specified for the grade:

(1) When a tolerance is 10 percent or more, not more than one-tenth of the 

individual containers in any lot may contain more than one and one-half 

times the tolerance specified, except that at least one defective and one 

off-sized specimen may be permitted in a container.

(2) When tolerance is less than 10 percent, not more than one-tenth of the 

individual containers in any lot may contain more than double the 

tolerance specified, but no package may contain more than four times the 

tolerance for soft rot or wet breakdown, except that at least one defective 

and one off-sized specimen may be permitted in a container.

Definitions

§51.1580 Fairly well shaped.

“Fairly well shaped” means that the appearance of the individual potato or the general 

appearance of the potatoes in the container is not materially injured by pointed, 

dumbbell-shaped or otherwise ill-formed potatoes.
United States Consumer Standards for Potatoes (December 8, 1947)

4

§51.1581 Fairly clean.

“Fairly Clean” means that from the viewpoint of general appearance, that potatoes in the 

container are reasonably free from dirt or other foreign matter, and that individual 

potatoes are not materially caked with dirt or materially stained.

§51.1582 Soft rot or wet breakdown.

“Soft rot or wet breakdown” means any soft, mushy, or leaky condition of the tissue

such as slimy soft rot, leak, or wet breakdown following freezing injury, scald, or other 

injury.

§51.1583 Damage.

“Damage” means any injury or defect which materially injures the edible or shipping 

quality, or the appearance of the individual potato or the general appearance of the 

potatoes in the container, or which cannot be removed without a loss of more than 5 

percent of the total weight of the potato including peel covering defective area. Loss of 

outer skin (epidermis) shall not be considered as damage when the potatoes are 

designated an “Early” unless the skinned surface is materially affected by dark 

discoloration. Any one of the following defects, or any combination of defects, the 

seriousness of which exceeds the maximum allowed for any one defect, shall be 

considered as damage: 

(a) Second growth or growth cracks which have developed to such an extent as 

to materially injure the appearance of the individual potato or the general 

appearance of the potatoes in the container.

(b) Air cracks which are deep, or shallow air cracks which materially injure the 

appearance of the individual potato or the general appearance of the potatoes in 

the container.

(c) Shriveling, when the potato is more than moderately shriveled, spongy, or 

flabby.

(d) Sprouting, when the sprouts are not dried and are more than one-half inch long.

(e) Surface scab which covers an area of more than 5 percent of the surface of the 

potato in the aggregate.

(f) Pitted scab which affects the appearance of the potato to a greater extent than 

the amount of surface scab permitted or causes a loss of more than 5 percent of 

the total weight of the potato including peel covering defective area.

(g) Rhizoctonia, when the general appearance of the potatoes in the container is 

materially injured or when individual potatoes are badly infected.

(h) Wireworm, grass root or similar injury, when any hole on potatoes ranging in 
United States Consumer Standards for Potatoes (December 8, 1947)

5

size from 6 to 8 ounces is longer than three-fourths inch, or when the aggregate 

length of all holes is more than one and one-fourth inches; smaller potatoes shall 

have lesser amounts and larger potatoes may have greater amounts; Provided, 

That the removal of the injury by proper trimming does not cause the appearance 

of such potatoes to be injured to a greater extent than that caused by the proper 

trimming of such injury permitted on a 6 to 8 ounce potato.

§51.1584 Internal discoloration.

“Internal discoloration” means discoloration such as is caused by net necrosis or any 

other type of necrosis, stem-end browning, internal brown spot, or other similar types of 

discoloration not visible externally.

§51.1585 Mature.

“Mature” means that the outer skin (epidermis) does not loosen or “feather” readily 

during the ordinary methods of handling.

§51.1586 Serious damage.

“Serious damage” means any injury or defect which seriously injures the edible or 

shipping quality, or the appearance of the individual potato or the general appearance of 

the potatoes in the container, or which cannot be removed without a loss of more than 

10 percent of the total weight of the potato including peel covering defective area. Any 

one of the following defect or any combination of defects the seriousness of which 

exceeds the maximum allowed for any one defect shall be considered as serious 

damage:

(a) Fairly smooth cuts such as are made by the digger, or by a knife to remove 

injury when both ends are clipped, or when more than an estimated one-fourth of 

the potato is cut away, or, in the case of long varieties, when the remaining 

portion of the clipped potato weighs less than 6 ounces; irregular types of cuts 

which seriously affect the appearance of the individual potato, or which cannot be 

removed without a loss of more than 10 percent of the total weight of the potato 

including peel covering defective area.

(b) Shriveling, when the potato is excessively shriveled, spongy, or flabby.

(c) Surface scab which covers an area of more than 50 percent of the surface of the 

potato in the aggregate.

(d) Pitted scab which affects the appearance of the potato to a greater extent than 

the amount of surface scab permitted or causes a loss of more than 10 percent 

of the total weight of the potato including peel covering defective area.

(e) Wireworm, grass root or similar injury, when any hole on potatoes ranging in 

size from 6 to 8 ounces is longer than one and one-fourth inches, or when the 
United States Consumer Standards for Potatoes (December 8, 1947)

6

aggregate length of all holes is more than two inches; smaller potatoes shall 

have lesser amounts and larger potatoes may have greater amounts; Provided, 

That the removal of the injury by proper trimming, does not cause the 

appearance of such potatoes to be injured to a greater extent than that caused 

by the proper trimming of such injury permitted on a 6 to 8 ounce potato.

§51.1587 Diameter.

“Diameter” means the greatest dimension at right angles to the longitudinal axis. The 

long axis shall be used without regard to the position of the stem (rhizome).