How to Calibrate a Food Thermometer: Ice Water and Boiling Water
A two-minute accuracy check from USDA FSIS that works for most thermometers.
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Ice water (best for most thermometers)
- Fill a large glass with ice cubes, add drinking water and stir.
- Put the stem at least 2 inches in, touching neither the sides nor the bottom.
- Wait at least 30 seconds and read it without removing the stem.
- It should read 32°F. If not, adjust per the maker instructions.
Boiling water (for higher temperatures)
- Bring clean water to a boil.
- Insert the stem at least 2 inches deep, away from the sides and bottom, and wait at least 30 seconds.
- It should read 212°F at sea level. At high altitude, USDA FSIS says water boils lower by at least 2°F and perhaps by as much as 5°F; ask your local Cooperative Extension office.
Next, learn which thermometer type suits each job, then cook to the safe temperatures chart.
Frequently asked questions
How accurate are most food thermometers?
USDA FSIS says most give an accurate reading within 2 to 4°F, if placed correctly.
What if my thermometer cannot be adjusted?
USDA FSIS says you may need to replace it.
