How to Calibrate a Digital Thermometer

Calibrate your digital thermometer using ice or hot water.

Available in a variety of models and sizes, digital thermometers measure temperature and outputs the measurement on a display similar to a calculator screen. The instruments are used in medical, food, human, industrial and other environments. Like there non-digital counterparts, you need to calibrate your digital thermometer to ensure it provides an accurate reading. Calibration is needed before using the thermometer for the first time; if you use the thermometer to measure both hot and cold temperatures; if you drop the thermometer; and if you use the digital thermometer multiple times during the same day.

Things You'll Need

• Insulated glass
• Crushed ice
• Blender (optional)
• Water
• Pot
• Stove, burner or other heat source

Instructions

Calibrating – Using Ice

1. Fill an insulated glass with crushed ice from a ice machine or by grinding ice cubes with a blender.

2. Add 1/2 cup of water from a sink. Let the ice mixture sit for five minutes.

3. Insert the sensing end of your digital thermometer into the center of the ice mixture. Push the thermometer to the middle of the glass.

4. Let the digital thermometer sit in the ice mixture for 30 seconds. The thermometer should display 32 degrees F on its display.

   If the thermometer reads “Error” or another temperature, repeat steps 3 and 4.

5. Press the “Reset” button on the side of your thermometer. Your digital thermometer is now calibrated.

Calibrating – Using Boiling Water

1. Fill a pot with 3 cups of water from a sink. Bring the water to a boil on a stove, burner or other heat source. Turn off the pot once the water is boiling.

2. Insert the sensing end of your digital thermometer into the center of the hot water. Push the thermometer to the middle of the water.

3. Let the digital thermometer sit in the water for 30 seconds. The thermometer should display 212 degrees F on its display, if you are at 1,000 feet elevation or less.

   If the thermometer reads “Error” or another temperature, repeat steps 2 and 3.

4. Press the “Reset” button on the side of your thermometer. Your digital thermometer is now calibrated.

Tips & Warnings

• If completing steps in the “Calibrating – Using Boiling Water” section and you are at an elevation between 1,000 and 1,999 feet, the temperature to calibrate your digital thermometer at is 210 degrees F; between 2,000 and 2,999 feet, calibrate at 208 degrees F; between 3000 and 3,999 feet, 206.4 degrees F; between 4,000 and 4,999 feet, 204.5 degrees F; between 5,000 and 5,999 feet, 202.75 degrees F; and 8,000 feet and higher, 197.5 degrees F.

• Using the ice mixture method provides the most accurate calibration.

References

• Canada Cutlery: To Calibrate A Thermometer Is Actually A Very Simple Process
• Food Service: How To Calibrate A Thermometer

Resources

• Dr Spock: Thermometers: Types and Techniques