Kitchen Thermometers
United States Department of Agriculture
Food Safety and Inspection Service
Food Safety Information
USDA Photo
Kitchen Thermometers
It 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.
Why Use a Food Thermometer?
USDA Photo
might continue cooking it until it is overcooked and
dry. However, a consumer using a food thermometer
Using a food thermometer is the only reliable way to
to check for “doneness” can feel assured the food
ensure safety and to determine desired “doneness”
has reached a safe temperature and is not
of meat, poultry, and egg products. To be safe, these
overcooked.
foods must be cooked to a safe minimum internal
temperature to destroy any harmful microorganisms
Likewise, all poultry should reach a safe minimum
that may be in the food.
internal temperature of 165 °F. For reasons of
personal preference, consumers may choose to cook
“Doneness” refers to when a food is cooked to a
poultry to higher temperatures for acceptability and
desired state and indicates the sensory aspects of
palatability.
foods such as texture, appearance, and juiciness.
Unlike the temperatures required for safety, these
A food thermometer should also be used to ensure
sensory aspects are subjective.
that cooked food is held at safe temperatures until
served. Cold food should be held at 40 °F or below.
Color is Not a Reliable Indicator
Hot food should be kept hot, at 140 °F or above.
Many food handlers believe that visible indicators,
Types of Thermometers
such as color changes, can be used to determine if
foods are cooked to a point where pathogens are
Food thermometers come in several types and styles,
killed. However, recent research has shown that
and vary in level of technology and price.
color and texture indicators are unreliable. For
example, ground beef may turn brown before it
Digital Food Thermometers
reaches a temperature where pathogens are
destroyed. A consumer preparing hamburger patties
Thermocouple:
and using the brown color as an indicator of
“doneness” is taking a chance that pathogenic
Of all food
microorganisms may survive. A hamburger cooked to
thermometers,
160 °F, regardless of color, is safe.
thermocouple
thermometers reach
Safety Versus Doneness
and display the final
temperature the
The temperature at which different pathogenic
fastest - within 2 to
microorganisms are destroyed varies, as does the
5 seconds. The
“doneness” temperature for different meat and
temperature is
poultry. A beef, lamb, or veal roast, steak, or chop
indicated on a digital
that is not pierced in any way during processing or
display.
preparation and reaches an internal temperature of
145 °F is safe to eat. Cook steaks, roasts, or chops
A thermocouple measures temperature at the
that have been tenderized, boned, rolled, etc., to a
junction of two fine wires located in the tip of the
safe minimum internal temperature of 160 °F. A pork
probe. Thermocouples used in scientific laboratories
chop or roast cooked to 160 °F is safe to eat. A
have very thin probes, similar to hypodermic needles,
consumer looking for a visual sign of “doneness”
while others may have a thickness of 1/ 16 of an inch.
The Food Safety and Inspection Service (FSIS) is the public health
USDA Meat & Poultry Hotline
agency in the U.S. Department of Agriculture responsible for ensuring
that the nation’s commercial supply of meat, poultry, and egg products
1-888-MPHotline
is safe, wholesome, and correctly labeled and packaged.
(1-888-674-6854)
Kitchen Thermometers
Since thermocouple thermometers respond so rapidly,
Thermometer Fork Combination:
the temperature can be quickly checked in a number
of locations to ensure that the food is safely cooked.
This utensil combines a cooking
This is especially useful for cooking large foods, such
fork with a food thermometer. A
as roasts or turkeys, when checking the temperature
temperature-sensing device is
in more than one place is advised. The thin probe of
embedded in one of the tines of
the thermocouple also enables it to accurately read
the fork. There are several
the temperature of thin foods such as hamburger
different brands and styles of
patties, pork chops, and chicken breasts.
thermometer forks on the
market; some using
Thermocouples are not designed to remain in the food
thermocouples and some using
while it’s cooking. They should be used near the end
thermistors. The food
of the estimated cooking time to check for final cooking
temperature is indicated on a
temperatures. To prevent overcooking, check the tem-
digital display or by indicator
perature before the food is expected to finish cooking.
lights on the handle within 2 to
10 seconds (depending on the type). These lights
Thermocouples can be calibrated for accuracy.
will tell if the food has reached rare, medium, well
done, etc. Particularly useful for grilling, the
Thermistors:
thermometer fork will accurately measure the
internal temperature of even the thinnest foods. The
Thermistor-style food
thermometer fork should be used to check the
thermometers use a
temperature of a food towards the end of the
resistor (a ceramic
estimated cooking time. Thermometer forks are not
semiconductor bonded in
designed to remain in a food while in the oven or on
the tip with temperature-
the grill. Thermometer forks cannot be calibrated.
sensitive epoxy) to
measure temperature. The
Dial Food Thermometers
thickness of the probe is approximately 1/ 8 of an
inch and takes roughly 10 seconds to register the
Bimetallic-coil Thermometers:
temperature on the digital display. Since the
semiconductor is in the tip, thermistors can measure
These thermometers contain a coil in the probe made
temperature in thin foods, as well as thick foods.
of two different metals that are bonded together.
Because the center of a food is usually cooler than
The two metals have different rates of expansion.
the outer surface, place the tip in the center of the
The coil, which is connected to the temperature
thickest part of the food.
indicator, expands when heated. This food
thermometer senses temperature from its tip and up
Thermistors are not designed to remain in the food
the stem for 2 to 2 1/ 2 inches. The resulting
while it’s cooking. They should be used near the end
temperature is an average of the temperatures
of the estimated cooking time to check for final
along the sensing area. These food thermometers
cooking temperatures. To prevent overcooking, check
have a dial display and are available as “oven-safe”
the temperature before the food is expected to finish
and “instant-read.”
cooking.
“Oven-safe” Bimetallic-coil Thermometers:
Not all thermistors can be calibrated. Check the
This food thermometer is
manufacturer’s instructions.
designed to remain in the
food while it is cooking in
Oven Cord Thermometers:
the oven, and is generally
used for large items such
This food thermometer allows the cook to check the
as a roast or turkey. This
temperature of food in the oven without opening the
food thermometer is
oven door. A base unit with a digital screen is
convenient because it
attached to a thermistor-type food thermometer
constantly shows the
probe by a long metal cord. The probe is inserted
temperature of the food
into the food, and the cord extends from the oven to
while it is cooking. However, if not left in the food
the base unit. The base can be placed on the
while cooking, they can take as long as 1 to 2
counter or attached to the stovetop or oven door by
minutes to register the correct temperature.
a magnet. The thermometer is programmed for the
desired temperature and beeps when it is reached.
The bimetal food thermometer can accurately
While designed for use in ovens, these
measure the temperature of relatively thick foods
thermometers can also be used to check foods
(such as beef roasts) or deep foods (foods in a
cooking on the stove. Oven cord thermometers
stockpot). Because the temperature-sensing coil on
cannot be calibrated.
the stem is between 2 to 2 1/ 2 inches long and the
Food Safety Information
2
Kitchen Thermometers
stem is relatively thick, it is not appropriate to
the temperature is reached. These sensors cannot
measure the temperature of any food less than 3
be left in a food while it is cooking. They should be
inches thick.
used near the end of the estimated cooking time. To
prevent overcooking, check the temperature before
There is concern that because heat conducts along
the food is expected to finish cooking.
the stem’s metal surface faster than through the
food, the area of the food in contact with the
Disposable temperature indicators are made from
thermometer tip will be hotter than the area a short
materials approved by the FDA for contact with food.
distance to the side (the “potato nail effect”). To
remedy this, the temperature should be taken in a
Pop-Up Timers:
second, and even third area, to verify the
Commonly used in
temperature of the food. Each time the thermometer
turkeys and roasting
is inserted into the food, let the thermometer
chickens since 1965, the
equilibrate (come to temperature) at least 1 minute
“pop-up” style
before reading the temperature.
disposable cooking
device is constructed of
Some models can be calibrated. Check the
food grade nylon. The
manufacturer’s instructions.
inside contains a
stainless steel spring
“Instant Read” Bimetallic-coil Thermometers:
and organic firing material. The organic firing material
This food thermometer
is specifically designed to dissolve at specific
quickly measures the
predetermined temperatures. Once the firing
temperature of a food in
material dissolves, the stainless steel spring
about 15 to 20 seconds.
releases the stem, allowing it to “pop up.” This
It is not designed to
indicates that the food has reached the correct final
remain in the food while it
temperature for safety and doneness. Pop-up style
is cooking in the oven,
disposable cooking devices are reliable and accurate
but should be used near the end of the estimated
to within 1 to 2 °F, however, proper placement is
cooking time to check for final cooking temperatures.
important. Checking with a conventional food
To prevent overcooking, check the temperature
thermometer is always recommended as an added
before the food is expected to finish cooking.
precaution to properly gauging both safety and
doneness.
For accurate temperature measurement, the probe
of the bimetallic-coil thermometer must be inserted
Other Types of Food Thermometers
the full length of the sensing area (usually 2 to 3
inches). If measuring the temperature of a thin food,
Liquid-filled Thermometers:
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
Also called “spirit-filled” or
positioned through the center of the food. Some
“liquid in glass” thermo-
models can be calibrated. Check the manufacturer’s
meters, these
instructions.
thermometers are the
oldest kind of food
Single-Use Temperature Indicators
thermometer used in home kitchens. They have
either metal or glass stems. As the internal
temperature of the food increases, the colored liquid
One of the most recent developments in the retail
inside the stem expands and rises to indicate the
food market is the emergence of disposable
temperature on a scale. Heat conduction in the metal
temperature indicators. Several brands are available,
stems can cause false high readings. They are
and all make quick work of determining if a food has
designed to remain in the food while it is cooking.
reached its final temperature. These temperature
They should be inserted at least 2 inches deep in the
sensors are designed for specific temperature
thickest part of the food, and are, therefore, not
ranges, for example, 160 -170 °F. It is important that
appropriate for thin foods. Some liquid-filled
the sensors be used only with foods for which they
thermometers can be calibrated by carefully moving
are intended. Read the package directions to ensure
the glass stem within the holder.
that the temperature the sensor will reach is
consistent with the safe temperatures listed in this
Candy/Jelly/Deep Fry Thermometers:
publication.
The sensors are made from special temperature-
These thermometers will
sensitive materials. The sensor is inserted into a
measure temperatures
food. When the food reaches the safe temperature,
ranging from 100 to 400
the sensor changes color. They are designed to be
°F. They are used to
used only once. However, if the desired temperature
measure the extra-high temperatures required of
has not been reached, they can be reinserted until
candy and jelly making, as well as frying with hot oil.
Food Safety Information
3
Kitchen Thermometers
Appliance Thermometers
Refrigerator/ Freezer Thermometers:
in the event of a power outage. When the power
For safety, it is important to verify
goes back on, if the refrigerator is 40 °F or below,
the temperature of refrigerators
and the freezer is still colder than 40 °F, the food is
and freezers. Refrigerators
safe. These bimetallic-coil thermometers are specially
should maintain a temperature of
designed to provide accuracy at cold temperatures.
40 °F or below. Frozen food will
hold its top quality for the
Oven Thermometers:
longest possible time when the
An oven thermometer can be left in
freezer maintains 0 °F or below.
the oven to verify that the oven is
An appliance thermometer can be
heating to the desired
kept in the refrigerator and
temperatures. These bimetallic-coil
freezer to monitor the
thermometers can measure
temperature. This can be critical
temperatures from 100 to 600 °F.
FOOD THERMOMETERS
Types
Speed
Placement
Usage Considerations
Digital Thermometers
Thermocouple
2- 5 seconds
1/ 4" or deeper in
• Gives fastest reading
the food, as needed
• 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
Thermistor
10 seconds
At least 1/ 2" deep
• Gives fast reading
in the food
• 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
Oven Cord
10 seconds
At least 1/ 2" deep
• Can be used in most foods
Thermometer
in the food
• 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
Thermometer
2- 10
At least 1/ 4" in the
• Can be used in most foods
Fork
seconds
thickest part of food
• Not designed to remain in food while it is
Combination
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
Food Safety Information
4
Kitchen Thermometers
Dial Thermometers
Types
Speed
Placement
Usage Considerations
Oven-Safe,
1- 2
2- 2 1/ 2" deep in
•
Can be used in roasts, casseroles,
Bimetal
minutes
the thickest part of
and soups
the food
•
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
Instant-Read,
15- 20
2- 2 1/ 2" deep in
•
Can be used in roasts, casseroles,
Bimetal
seconds
the thickest part of
and soups
the food
•
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
Other
Types
Speed
Placement
Usage Considerations
Single-Use
5- 10
Approx. 1/ 2" deep
•
Designed to be used only once
Temperature
seconds
(follow
•
Designed for specific temperature
Indicators
manufacturer’s
ranges
directions)
•
Should only be used with food for
which they are intended
•
Temperature-sensitive material
changes color when the desired
temperature is reached
Liquid-Filled
1- 2
At least 2" deep in
•
Used in roasts, casseroles, and soups
(glass or metal
minutes
the thickest part of
•
Can remain in food while it’s cooking
stem)
the food
•
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
Food Safety Information
5
Kitchen Thermometers
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, institu-
tional, 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
160
Turkey, Chicken
165
Fresh Beef, Veal, Lamb
Medium Rare
145
Medium
160
Well Done
170
Poultry
Chicken and Turkey, whole
165
Poultry breasts, roasts
165
Poultry thighs, wings
165
Duck and Goose
165
Stuffing (cooked alone or in bird)
165
Fresh Pork
160
Ham
Fresh (raw)
160
Pre-cooked (to reheat)
140
Eggs and Egg Dishes
Eggs
Cook until yolk and
white are firm
Egg dishes
160
Leftovers and Casseroles
165
Food Safety Information
6
Kitchen Thermometers
Using the Food Thermometer
Thin Foods
Most available food thermometers will give an
When measuring the temperature of a thin food,
accurate reading within 2 to 4 °F. The reading will
such as a hamburger patty, pork chop, or chicken
only be correct, however, if the thermometer is
breast, a thermistor or thermocouple food
placed in the proper location in the food. If not
thermometer should be used, if possible.
inserted correctly, or if the food thermometer is
placed in the wrong area, the reading will not
However, if using an “instant-read” dial bimetallic-coil
accurately reflect the internal temperature of the
food thermometer, the probe must be inserted in the
food. In general, the food thermometer should be
side of the food so the entire sensing area (usually
placed in the thickest part of the food, away from
2-3 inches) is positioned through the center of the
bone, fat, or gristle.
food.
Check Manufacturer’s Instructions
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
Before using a food thermometer, read the
sideways after placing the item on a clean spatula or
manufacturer’s instructions first. The instructions
plate.
should tell how far the thermometer must be
inserted in a food to give an accurate reading. If
Combination Dishes
instructions are not available, check the stem of the
food thermometer for an indentation, or “dimple.”
For casseroles and other combination dishes, place
This shows one end of the location of the sensing
the food thermometer into the thickest portion of the
device. Dial thermometers must penetrate about 2 to
food or the center of the dish. Egg dishes and dishes
3 inches into the food. Most digital thermometers will
containing ground meat and poultry should be
read the temperature in a small area of the tip.
checked in several places.
Where to Place the Food Thermometer
Thermometer Care
Meat
As with any cooking utensil, food thermometers
should be washed with hot soapy water. Most
When taking the temperature of beef, pork, or lamb
thermometers should not be immersed in water.
roasts, the food thermometer should be placed
Wash carefully by hand.
midway in the roast, avoiding the bone. When
cooking hamburgers, steaks, or chops, insert a
Use caution when using a food thermometer. Some
thermistor or thermocouple in the thickest part, away
models have plastic faces, which can melt if placed
from bone, fat, or gristle. If using a dial bimetal
too close to heat or dropped in hot liquid.
thermometer, read “Thin Foods” below.
Thermometer probes are sharp and should be stored
When the food being cooked is irregularly shaped,
with the probe in the stem sheath. Some glass
such as with a beef roast, check the temperature in
thermometers are sensitive to rough handling and
several places.
should be stored in their packaging for extra
protection or in a location where they will not be
Poultry
jostled.
FSIS recommends cooking whole poultry to a safe
Calibrating a Thermometer
minimum internal temperature of 165 °F as
measured with a food thermometer. Check the
internal temperature in the innermost part of the
There are two ways to check the accuracy of a food
thigh and wing and the thickest part of the breast.
thermometer. One method uses ice water, the other
For reasons of personal preference, consumers may
uses boiling water. Many food thermometers have a
choose to cook poultry to higher temperatures. For
calibration nut under the dial that can be adjusted.
optimum safety, do not stuff poultry. If stuffing whole
Check the package for instructions.
poultry, the center of the stuffing must reach a safe
minimum internal temperature of 165 °F. If cooking
Ice Water
poultry parts, insert food thermometer into the
thickest area, avoiding the bone. The food
To use the ice water method, fill a large glass with
thermometer may be inserted sideways if necessary.
finely crushed ice. Add clean tap water to the top of
When the food is irregularly shaped, the
the ice and stir well. Immerse the food thermometer
temperature should be checked in several places.
stem a minimum of 2 inches into the mixture,
touching neither the sides nor the bottom of the
Food Safety Information
7
Kitchen Thermometers
glass. Wait a
water in unknown atmospheric conditions would
minimum of 30
probably not measure water boiling at 212 °F. Most
seconds before
likely it would boil at least 2 °F, and perhaps as much
adjusting. (For ease
as 5 °F, lower. Remember that water boils at a lower
in handling, the
temperature in a high altitude area. Check with the
stem of the food
local Cooperative Extension Service or Health
thermometer can be
Department for the exact temperature of boiling
placed through the
water.
clip section of the
stem sheath and,
Even if the food
holding the sheath
thermometer
horizontally,
cannot be
lowered into the
calibrated, it
water.) Without
should still be
removing the stem from the ice, hold the adjusting
checked for
nut under the head of the thermometer with a
accuracy using
suitable tool and turn the head so the pointer reads
either method.
32 °F.
Any inaccuracies
can be taken into
Boiling Water
consideration
when using the
To use the boiling water method, bring a pot of
food thermometer, or the food thermometer can be
clean tap water to a full rolling boil. Immerse the
replaced. For example, water boils at 212 °F. If the
stem of a food thermometer in boiling water a
food thermometer reads 214 °F in boiling water, it is
minimum of 2 inches and wait at least 30 seconds.
reading 2 degrees too high. Therefore 2 degrees
(For ease in handling, the stem of the food
must be subtracted from the temperature displayed
thermometer can be placed through the clip section
when taking a reading in food to find out the true
of the stem sheath and, holding the sheath
temperature. In another example, for safety, ground
horizontally, lowered into the boiling water.) Without
beef patties must reach 160 °F. If the thermometer is
removing the stem from the pan, hold the adjusting
reading 2 degrees too high, 2 degrees would be
nut under the head of the food thermometer with a
added to the desired temperature, meaning
suitable tool and turn the head so the thermometer
hamburger patties must be cooked to 162 °F.
reads 212 °F.
For true accuracy, distilled water must be used and
“Is it done yet?” You can’t tell by looking. Use a food
the atmospheric pressure must be one atmosphere
thermometer to be sure.
(29.921 inches of mercury). A consumer using tap
www.IsItDoneYet.gov
Food Safety Questions?
Call the USDA Meat & Poultry Hotline
Ask Karen!
If you have a question
The Hotline is open year-round
FSIS’ automated response
about meat, poultry, or
Monday through Friday
system can provide food safety
egg products, call the
from 10 a.m. to 4 p.m.
information 24/7
USDA Meat and
ET (English or
Poultry Hotline
Spanish). Recorded
toll free at
food safety messages
1-888-MPHotline
are available 24 hours
(1-888-674-6854);
a day. Check out the
TTY: 1-800-256-7072.
FSIS Web site at
www.fsis.usda.gov.
Send E-mail questions to MPHotline.fsis@usda.gov.
AskKaren.gov
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Revised June 2008
