Kitchen Thermometers

USDA Meat & Poultry Hotline

1-888-MPHotline

(1-888-674-6854)

The Food Safety and Inspection Service (FSIS) is the public health

agency in the U.S. Department of Agriculture responsible for ensuring

that the nation’s commercial supply of meat, poultry, and egg products

is safe, wholesome, and correctly labeled and packaged.

Food Safety Information

United States Department of Agriculture

Food Safety and Inspection Service

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USDA Photo

Why Use a Food Thermometer?

Using a food thermometer is the only reliable way to

ensure safety and to determine desired “doneness”

of meat, poultry, and egg products. To be safe, these

foods must be cooked to a safe minimum internal

temperature to destroy any harmful microorganisms

that may be in the food.

“Doneness” refers to when a food is cooked to a

desired state and indicates the sensory aspects of

foods such as texture, appearance, and juiciness.

Unlike the temperatures required for safety, these

sensory aspects are subjective.

Color is Not a Reliable Indicator

Many food handlers believe that visible indicators,

such as color changes, can be used to determine if

foods are cooked to a point where pathogens are

killed. However, recent research has shown that

color and texture indicators are unreliable. For

example, ground beef may turn brown before it

reaches a temperature where pathogens are

destroyed. A consumer preparing hamburger patties

and using the brown color as an indicator of

“doneness” is taking a chance that pathogenic

microorganisms may survive. A hamburger cooked to

160 °F, as measured with a meat thermometer,

regardless of color, is safe.

Safety Versus Doneness

The temperature at which different pathogenic

microorganisms are destroyed varies, as does the

“doneness” temperature for different meat and

poultry. A consumer looking for a visual sign of

“doneness” might continue cooking it until it is

overcooked and dry. However, a consumer using a

food thermometer to check for “doneness” can feel

assured the food has reached a safe temperature

and is not overcooked. Cook all raw beef, pork,

I

t is essential to use a food thermometer when cooking meat, poultry, and egg products to prevent

undercooking, verify that food has reached a safe minimum internal temperature, and consequently, prevent

foodborne illness.

lamb and veal steaks, chops, and roasts to a

minimum internal temperature of 145°F as measured

with a food thermometer before removing meat from

the heat source. For safety and quality, allow meat to

rest for at least three minutes before carving or

consuming. For reasons of personal preference,

consumers may choose to cook meat to higher

temperatures.

Cook all poultry to a safe minumum internal

temperature of 165°F as measured with a food

thermometer. For reasons of personal preference,

consumers may choose to cook meat to higher

temperatures.

A food thermometer should also be used to ensure

that cooked food is held at safe temperatures until

served. Cold food should be held at 40 °F or below.

Hot food should be kept hot, at 140 °F or above.

Types of Thermometers

Food thermometers come in several types and styles,

and vary in level of technology and price.

Digital Food

Thermometers

Thermocouple:

Of all food

thermometers,

thermocouple

thermometers reach

and display the final

temperature the fastest - within 2 to 5 seconds. The

temperature is indicated on a digital display.

A thermocouple measures temperature at the

junction of two fine wires located in the tip of the

probe. Thermocouples used in scientific laboratories

have very thin probes, similar to hypodermic needles,

while others may have a thickness of 1/ 16 of an inch.
Kitchen Thermometers

Food Safety Information 2

Since thermocouple thermometers respond so rapidly,

the temperature can be quickly checked in a number

of locations to ensure that the food is safely cooked.

This is especially useful for cooking large foods, such

as roasts or turkeys, when checking the temperature

in more than one place is advised. The thin probe of

the thermocouple also enables it to accurately read

the temperature of thin foods such as hamburger

patties, pork chops, and chicken breasts.

Thermocouples are not designed to remain in the food

while it’s cooking. They should be used near the end

of the estimated cooking time to check for final cooking

temperatures. To prevent overcooking, check the temperature before the food is expected to finish cooking.

Thermocouples can be calibrated for accuracy.

Thermistors:

Thermistor-style food

thermometers use a

resistor (a ceramic

semiconductor bonded in

the tip with temperaturesensitive epoxy) to

measure temperature. The

thickness of the probe is approximately 1/ 8 of an

inch and takes roughly 10 seconds to register the

temperature on the digital display. Since the

semiconductor is in the tip, thermistors can measure

temperature in thin foods, as well as thick foods.

Because the center of a food is usually cooler than

the outer surface, place the tip in the center of the

thickest part of the food.

Thermistors are not designed to remain in the food

while it’s cooking. They should be used near the end

of the estimated cooking time to check for final

cooking temperatures. To prevent overcooking, check

the temperature before the food is expected to finish

cooking.

Not all thermistors can be calibrated. Check the

manufacturer’s instructions.

Oven Cord Thermometers:

This food thermometer allows the cook to check the

temperature of food in the oven without opening the

oven door. A base unit with a digital screen is

attached to a thermistor-type food thermometer

probe by a long metal cord. The probe is inserted

into the food, and the cord extends from the oven to

the base unit. The base can be placed on the

counter or attached to the stovetop or oven door by

a magnet. The thermometer is programmed for the

desired temperature and beeps when it is reached.

While designed for use in ovens, these

thermometers can also be used to check foods

cooking on the stove. Oven cord thermometers

cannot be calibrated.

Thermometer Fork Combination:

This utensil combines a cooking

fork with a food thermometer. A

temperature-sensing device is

embedded in one of the tines of

the fork. There are several

different brands and styles of

thermometer forks on the

market; some using

thermocouples and some using

thermistors. The food

temperature is indicated on a

digital display or by indicator

lights on the handle within 2 to

10 seconds (depending on the type). These lights

will tell if the food has reached rare, medium, well

done, etc. Particularly useful for grilling, the

thermometer fork will accurately measure the

internal temperature of even the thinnest foods. The

thermometer fork should be used to check the

temperature of a food towards the end of the

estimated cooking time. Thermometer forks are not

designed to remain in a food while in the oven or on

the grill. Thermometer forks cannot be calibrated.

Dial Food Thermometers

Bimetallic-coil Thermometers:

These thermometers contain a coil in the probe made

of two different metals that are bonded together.

The two metals have different rates of expansion.

The coil, which is connected to the temperature

indicator, expands when heated. This food

thermometer senses temperature from its tip and up

the stem for 2 to 2 1/ 2 inches. The resulting

temperature is an average of the temperatures

along the sensing area. These food thermometers

have a dial display and are available as “oven-safe”

and “instant-read.”

“Oven-safe” Bimetallic-coil Thermometers:

This food thermometer is

designed to remain in the

food while it is cooking in

the oven, and is generally

used for large items such

as a roast or turkey. This

food thermometer is

convenient because it

constantly shows the

temperature of the food

while it is cooking. However, if not left in the food

while cooking, they can take as long as 1 to 2

minutes to register the correct temperature.

The bimetal food thermometer can accurately

measure the temperature of relatively thick foods

(such as beef roasts) or deep foods (foods in a

stockpot). Because the temperature-sensing coil on

the stem is between 2 to 2 1/ 2 inches long and the
Kitchen Thermometers

Food Safety Information 3

stem is relatively thick, it is not appropriate to

measure the temperature of any food less than 3

inches thick.

There is concern that because heat conducts along

the stem’s metal surface faster than through the

food, the area of the food in contact with the

thermometer tip will be hotter than the area a short

distance to the side (the “potato nail effect”). To

remedy this, the temperature should be taken in a

second, and even third area, to verify the

temperature of the food. Each time the thermometer

is inserted into the food, let the thermometer

equilibrate (come to temperature) at least 1 minute

before reading the temperature.

Some models can be calibrated. Check the

manufacturer’s instructions.

“Instant Read” Bimetallic-coil Thermometers:

This food thermometer

quickly measures the

temperature of a food in

about 15 to 20 seconds.

It is not designed to

remain in the food while it

is cooking in the oven,

but should be used near the end of the estimated

cooking time to check for final cooking temperatures.

To prevent overcooking, check the temperature

before the food is expected to finish cooking.

For accurate temperature measurement, the probe

of the bimetallic-coil thermometer must be inserted

the full length of the sensing area (usually 2 to 3

inches). If measuring the temperature of a thin food,

such as a hamburger patty or boneless chicken

breast, the probe should be inserted through the

side of the food so that the entire sensing area is

positioned through the center of the food. Some

models can be calibrated. Check the manufacturer’s

instructions.

Single-Use Temperature Indicators

One of the most recent developments in the retail

food market is the emergence of disposable

temperature indicators. Several brands are available,

and all make quick work of determining if a food has

reached its final temperature. These temperature

sensors are designed for specific temperature

ranges, for example, 160 -170 °F. It is important that

the sensors be used only with foods for which they

are intended. Read the package directions to ensure

that the temperature the sensor will reach is

consistent with the safe temperatures listed in this

publication.

The sensors are made from special temperaturesensitive materials. The sensor is inserted into a

food. When the food reaches the safe temperature,

the sensor changes color. They are designed to be

used only once. However, if the desired temperature

has not been reached, they can be reinserted until

the temperature is reached. These sensors cannot

be left in a food while it is cooking. They should be

used near the end of the estimated cooking time. To

prevent overcooking, check the temperature before

the food is expected to finish cooking.

Disposable temperature indicators are made from

materials approved by the FDA for contact with food.

Pop-Up Timers:

Commonly used in

turkeys and roasting

chickens since 1965, the

“pop-up” style

disposable cooking

device is constructed of

food grade nylon. The

inside contains a

stainless steel spring

and organic firing material. The organic firing material

is specifically designed to dissolve at specific

predetermined temperatures. Once the firing

material dissolves, the stainless steel spring

releases the stem, allowing it to “pop up.” This

indicates that the food has reached the correct final

temperature for safety and doneness. Pop-up style

disposable cooking devices are reliable and accurate

to within 1 to 2 °F, however, proper placement is

important. Checking with a conventional food

thermometer is always recommended as an added

precaution to properly gauging both safety and

doneness.

Other Types of Food Thermometers

Liquid-filled Thermometers:

Also called “spirit-filled” or

“liquid in glass” thermometers, these

thermometers are the

oldest kind of food

thermometer used in home kitchens. They have

either metal or glass stems. As the internal

temperature of the food increases, the colored liquid

inside the stem expands and rises to indicate the

temperature on a scale. Heat conduction in the metal

stems can cause false high readings. They are

designed to remain in the food while it is cooking.

They should be inserted at least 2 inches deep in the

thickest part of the food, and are, therefore, not

appropriate for thin foods. Some liquid-filled

thermometers can be calibrated by carefully moving

the glass stem within the holder.

Candy/Jelly/Deep Fry Thermometers:

These thermometers will

measure temperatures

ranging from 100 to 400

°F. They are used to

measure the extra-high temperatures required of

candy and jelly making, as well as frying with hot oil.
Kitchen Thermometers

Food Safety Information 4

Appliance Thermometers

Refrigerator/ Freezer Thermometers:

For safety, it is important to verify

the temperature of refrigerators

and freezers. Refrigerators

should maintain a temperature of

40 °F or below. Frozen food will

hold its top quality for the

longest possible time when the

freezer maintains 0 °F or below.

An appliance thermometer can be

kept in the refrigerator and

freezer to monitor the

temperature. This can be critical

in the event of a power outage. When the power

goes back on, if the refrigerator is 40 °F or below,

and the freezer is still colder than 40 °F, the food is

safe. These bimetallic-coil thermometers are specially

designed to provide accuracy at cold temperatures.

Oven Thermometers:

An oven thermometer can be left in

the oven to verify that the oven is

heating to the desired

temperatures. These bimetallic-coil

thermometers can measure

temperatures from 100 to 600 °F.

Types

Thermocouple

Thermistor

Oven Cord

Thermometer

Thermometer

Fork

Combination

Speed

2- 5 seconds

10 seconds

10 seconds

2- 10

seconds

Placement

1/ 4" or deeper in

the food, as needed

At least 1/ 2" deep

in the food

At least 1/ 2" deep

in the food

At least 1/ 4" in the

thickest part of food

Usage Considerations

· Gives fastest reading

· Good for measuring temperatures of thick

and thin foods

· Not designed to remain in food while it’s

cooking

· Check internal temperature of food near

the end of cooking time

· Can be calibrated

· More costly; may be difficult for

consumers to find in stores

· Gives fast reading

· Can measure temperature in thin and

thick foods

· Not designed to remain in food while it’s

cooking

· Check internal temperature of food near

the end of cooking time

· Some models can be calibrated; check

manufacturer’s instructions

· Available in “kitchen” stores

· Can be used in most foods

· Can also be used outside the oven

· Designed to remain in the food while it is

cooking in oven or in covered pot

· Base unit sits on stovetop or counter

· Cannot be calibrated

· Can be used in most foods

· Not designed to remain in food while it is

cooking

· Sensor in tine of fork must be fully

inserted

· Check internal temperature of food near

the end of cooking time

· Cannot be calibrated

· Convenient for grilling

Digital Thermometers

FOOD THERMOMETERS
Kitchen Thermometers

Food Safety Information 5

Speed Placement Usage Considerations

1- 2

minutes

15- 20

seconds

Speed

5- 10

seconds

1- 2

minutes

Types

Oven-Safe,

Bimetal

Instant-Read,

Bimetal

Types

Single-Use

Temperature

Indicators

Liquid-Filled

(glass or metal

stem)

Dial Thermometers

· Can be used in roasts, casseroles,

and soups

· Not appropriate for thin foods

· Can remain in food while it’s cooking

· Heat conduction of metal stem can

cause false high reading

· Some models can be calibrated; check

manufacturer’s instructions

· Can be used in roasts, casseroles,

and soups

· Temperature is averaged along

probe, from tip to 2- 3" up the stem

· Cannot measure thin foods unless

inserted sideways

· Not designed to remain in food while

it is cooking

· Use to check the internal temperature

of a food at the end of cooking time

· Some models can be calibrated; check

manufacturer’s instructions

· Readily available in stores

Usage Considerations

· Designed to be used only once

· Designed for specific temperature

ranges

· Should only be used with food for

which they are intended

· Temperature-sensitive material

changes color when the desired

temperature is reached

· Used in roasts, casseroles, and soups

· Can remain in food while it’s cooking

· Cannot measure thin foods

· Some can be calibrated; check

manufacturer’s instructions

· Possible breakage of glass stem while

in food

· Heat conduction of metal stem can

cause false high reading

2- 2 1/ 2" deep in

the thickest part of

the food

2- 2 1/ 2" deep in

the thickest part of

the food

Placement

Approx. 1/ 2" deep

(follow

manufacturer’s

directions)

At least 2" deep in

the thickest part of

the food

Other
Kitchen Thermometers

Food Safety Information 6

Safety and Doneness

Most pathogens are destroyed between 140 and 165 °F. Higher temperatures may be necessary to

achieve consumer acceptability and palatability, also known as “doneness.”

These temperatures are recommended for consumer cooking. They are not intended for processing, institutional, or foodservice preparation. Food service professionals should consult their state or local food code.

Recommended Internal Temperatures*

Food °F

Ground Meat and Meat Mixtures

Beef, Pork, Veal, Lamb

Turkey, Chicken

Fresh Beef, Pork, Lamb & Veal

Beef, Pork, Veal, & Lamb (steaks, roasts and chops)

Ham

Fresh (raw)

Pre-cooked (to reheat)

Poultry

Chicken, Turkey, Duck & Goose (whole or pieces)

Poultry breast, roast

Stuffing (cooked alone or in bird)

Eggs and Egg Dishes

Eggs

Egg dishes

Leftovers and Casseroles

160

165

145**

145**

140

165

165

165

Cook until yolk and

white are firm

160

165

**as measured with a food thermometer before removing meat from the heat source. For safety and quality,

allow meat to rest for at least three minutes before carving or consuming. For reasons of personal preference,

consumers may choose to cook meat to higher temperatures.

*These temperatures are recommended for consumer cooking. They are not intended for processing,

institutional, or foodservice preparation. Food service professionals should consult their state or local

food code.
Kitchen Thermometers

Food Safety Information 7

Using the Food Thermometer

Most available food thermometers will give an

accurate reading within 2 to 4 °F. The reading will

only be correct, however, if the thermometer is

placed in the proper location in the food. If not

inserted correctly, or if the food thermometer is

placed in the wrong area, the reading will not

accurately reflect the internal temperature of the

food. In general, the food thermometer should be

placed in the thickest part of the food, away from

bone, fat, or gristle.

Check Manufacturer’s Instructions

Before using a food thermometer, read the

manufacturer’s instructions first. The instructions

should tell how far the thermometer must be

inserted in a food to give an accurate reading. If

instructions are not available, check the stem of the

food thermometer for an indentation, or “dimple.”

This shows one end of the location of the sensing

device. Dial thermometers must penetrate about 2 to

3 inches into the food. Most digital thermometers will

read the temperature in a small area of the tip.

Where to Place the Food Thermometer

Meat

When taking the temperature of beef, pork, or lamb

roasts, the food thermometer should be placed

midway in the roast, avoiding the bone. When

cooking hamburgers, steaks, or chops, insert a

thermistor or thermocouple in the thickest part, away

from bone, fat, or gristle. If using a dial bimetal

thermometer, read “Thin Foods” below.

When the food being cooked is irregularly shaped,

such as with a beef roast, check the temperature in

several places.

Poultry

FSIS recommends cooking whole poultry to a safe

minimum internal temperature of 165 °F as

measured with a food thermometer. Check the

internal temperature in the innermost part of the

thigh and wing and the thickest part of the breast.

For reasons of personal preference, consumers may

choose to cook poultry to higher temperatures. For

optimum safety, do not stuff poultry. If stuffing whole

poultry, the center of the stuffing must reach a safe

minimum internal temperature of 165 °F. If cooking

poultry parts, insert food thermometer into the

thickest area, avoiding the bone. The food

thermometer may be inserted sideways if necessary.

When the food is irregularly shaped, the

temperature should be checked in several places.

Thin Foods

When measuring the temperature of a thin food,

such as a hamburger patty, pork chop, or chicken

breast, a thermistor or thermocouple food

thermometer should be used, if possible.

However, if using an “instant-read” dial bimetallic-coil

food thermometer, the probe must be inserted in the

side of the food so the entire sensing area (usually

2-3 inches) is positioned through the center of the

food.

To avoid burning fingers, it may be helpful to remove

the food from the heat source (if cooking on a grill or

in a frying pan) and insert the food thermometer

sideways after placing the item on a clean spatula or

plate.

Combination Dishes

For casseroles and other combination dishes, place

the food thermometer into the thickest portion of the

food or the center of the dish. Egg dishes and dishes

containing ground meat and poultry should be

checked in several places.

Thermometer Care

As with any cooking utensil, food thermometers

should be washed with hot soapy water. Most

thermometers should not be immersed in water.

Wash carefully by hand.

Use caution when using a food thermometer. Some

models have plastic faces, which can melt if placed

too close to heat or dropped in hot liquid.

Thermometer probes are sharp and should be stored

with the probe in the stem sheath. Some glass

thermometers are sensitive to rough handling and

should be stored in their packaging for extra

protection or in a location where they will not be

jostled.

Calibrating a Thermometer

There are two ways to check the accuracy of a food

thermometer. One method uses ice water, the other

uses boiling water. Many food thermometers have a

calibration nut under the dial that can be adjusted.

Check the package for instructions.

Ice Water

To use the ice water method, fill a large glass with

finely crushed ice. Add clean tap water to the top of

the ice and stir well. Immerse the food thermometer

stem a minimum of 2 inches into the mixture,

touching neither the sides nor the bottom of the
Food Safety Questions?

Kitchen Thermometers

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Revised June 2011

FSIS encourages the reprint and distribution of this publication for food safety

education purposes. However, USDA symbols or logos may not be used

separately to imply endorsement of a commercial product or service.

Call the USDA Meat & Poultry Hotline

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glass. Wait a

minimum of 30

seconds before

adjusting. (For ease

in handling, the

stem of the food

thermometer can be

placed through the

clip section of the

stem sheath and,

holding the sheath

horizontally,

lowered into the

water.) Without

removing the stem from the ice, hold the adjusting

nut under the head of the thermometer with a

suitable tool and turn the head so the pointer reads

32 °F.

Boiling Water

To use the boiling water method, bring a pot of

clean tap water to a full rolling boil. Immerse the

stem of a food thermometer in boiling water a

minimum of 2 inches and wait at least 30 seconds.

(For ease in handling, the stem of the food

thermometer can be placed through the clip section

of the stem sheath and, holding the sheath

horizontally, lowered into the boiling water.) Without

removing the stem from the pan, hold the adjusting

nut under the head of the food thermometer with a

suitable tool and turn the head so the thermometer

reads 212 °F.

For true accuracy, distilled water must be used and

the atmospheric pressure must be one atmosphere

(29.921 inches of mercury). A consumer using tap

water in unknown atmospheric conditions would

probably not measure water boiling at 212 °F. Most

likely it would boil at least 2 °F, and perhaps as much

as 5 °F, lower. Remember that water boils at a lower

temperature in a high altitude area. Check with the

local Cooperative Extension Service or Health

Department for the exact temperature of boiling

water.

Even if the food

thermometer

cannot be

calibrated, it

should still be

checked for

accuracy using

either method.

Any inaccuracies

can be taken into

consideration

when using the

food thermometer, or the food thermometer can be

replaced. For example, water boils at 212 °F. If the

food thermometer reads 214 °F in boiling water, it is

reading 2 degrees too high. Therefore 2 degrees

must be subtracted from the temperature displayed

when taking a reading in food to find out the true

temperature. In another example, for safety, ground

beef patties must reach 160 °F. If the thermometer is

reading 2 degrees too high, 2 degrees would be

added to the desired temperature, meaning

hamburger patties must be cooked to 162 °F.

“Is it done yet?” You can’t tell by looking. Use a food

thermometer to be sure.

www.IsItDoneYet.gov

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