NDSU Extension - Sargent County


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When, Why and How to Test and Calibrate a Food Thermometer

When, Why and How to Test and Calibrate a Food Thermometer


A properly calibrated food thermometer is key for achieving both food safety and food quality.  Thermometers can get out of adjustment if they are jarred. Any time thermometers are dropped or exposed to extremes in temperatures, they should be calibrated. All thermometers— regardless of use—should be tested at least once a month to assure their accuracy.

To test a food thermometer:

Make a thick ice slush in a tall glass using crushed ice and cold water (50/50).

Insert the sensing area of thermometer into the center of the ice slush to a depth of at least two inches.  Do not let the thermometer touch the sides or bottom of the glass.

  • Allow enough time for the temperature indicator to stabilize.  This may take up to two minutes, depending on the type of thermometer being tested.    
  • If the thermometer reads 32°F, it is reading correctly and can be used.

However, if the temperature that registers during testing is inaccurate, make an adjustment.

  • If you are using a dial/gauge thermometer, adjust the dial/gauge by twisting the nut on the back (bottom or underside) of the thermometer.  You may need to use a pliers if it is too tight to turn with just your fingertips. Calibrate the thermometer again to ensure its accuracy prior to use.
  • If you are using a digital thermometer, you will not be able to make a manual adjustment.  Instead you will need to either replace the thermometer or calculate the inaccuracy (degree difference) and then appropriately add or subtract that number of degrees to mathematically adjust to the desired cooking temperature. 

A 3-minute video demonstration of thermometer calibration, recorded by University of California Davis Cooperative Extension Specialist Christine Bruhn, is available online at https://www.youtube.com/watch?v=PmfIywwuWfE&feature=youtu.be, or by searching “how to calibrate a meat thermometer North American Meat Institute”  The video does a very nice job of demonstrating and explaining the process of calibration and also how to make the mathematical calculations if/when the thermometer reads high or low.

Be sure to call me if you have questions or would like more information about food thermometers!

Source:  https://www.ag.ndsu.edu/publications/food-nutrition/keep-hot-foods-hot-and-cold-foods-cold-a-foodservice-guide-to-thermometers-and-safe-temperatures/fn712.pdf

Photo Source: https://pixabay.com/photos/thermometer-temperature-measure-428339/ (downloaded 12/15/20)

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