How to Calibrate a Thermometer

To ensure that your poultry is cooked to a safe temperature, without drying it out, or to accurately grill a steak to a medium-rare or well-done order, it is important to take a precise temperature reading. This can be accomplished with a properly calibrated food thermometer. Calibrating a thermometer can be done in a matter of minutes with a few supplies found in every kitchen. Calibrate a thermometer after it is purchased, if it is dropped, if it is being used between hot and cold temperature extremes and otherwise, at least monthly.

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Calibrate a dial stem or digital thermometer using the boiling or ice-point methods.

Ice Water Method

Step 1

Fill a glass with as much crushed ice as you can and fill the remainder of the space with distilled or filtered water. If you do not have distilled or filtered water, use clean tap water.

Step 2

Stir the ice chips and water.

Step 3

Insert the thermometer's probe or stem into the middle of the glass so that it is not touching the bottom or sides of the glass. Submerge at least 2 inches of the probe into the ice bath.

Step 4

Hold the stem in the ice bath for 30 to 60 seconds.

Step 5

Adjust the hex adjusting nut under the head or dial of the thermometer so that the temperature reads 32 degrees F, which is the freezing point of water. If you have a digital thermometer, press the reset button to adjust the temperature.

Boiling Water Method

Step 1

Pour tap water into a cooking pot and place it on the heat of a stove top element; bring the water to a rolling boil.

Step 2

Place the stem or probe into the boiling water so that at least 2 inches of the stem is immersed; the stem should not be touching the sides or the bottom of the pot.

Step 3

Hold the stem in the water for 30 to 60 seconds.

Step 4

Adjust the hex adjusting nut under the head or dial of the thermometer so that the temperature reads 212 degrees F, which is the boiling point of water. If you have a digital thermometer, press the reset button to adjust the temperature.