Calibrating your thermometer is one of the most important things you can do in preparation for cooking your Thanksgiving turkey. Why? If your thermometer isn’t calibrated you won’t get an accurate measurement of the internal temperature of the turkey as it cooks. If your thermometer is registering an inaccurately high temperature, your turkey will be undercooked, placing you and your guests at risk of getting sick. Or, if the thermometer is under-registering the temperature, your turkey will be overcooked, resulting in a dry, stringy bird.
Calibrating a thermometer is very easy. You should do it when you purchase a new thermometer, if you ever drop it, after you have used it outside at the barbecue grill, and periodically just to make sure it is accurate.
First fill a vessel, such as a pyrex measuring cup, with crushed ice. Add enough tap water to just cover the ice and fill the container.
Submerge the thermometer stem in the ice water bath. Hold it in the ice water until the reading stays steady, 30 seconds or more. Your thermometer should read 32 degrees, plus or minus 2 degrees. If it doesn’t you need to adjust your thermometer.
There is a calibration nut on the underside of your thermometer.
Using pliers you can move the temperature indicator on the front side of the thermometer. While holding the thermometer in the ice water, move the indicator to 32 degrees, plus or minus 2 degrees. Sometimes it’s very hard to get the thermometer to read 32 degrees exactly.
Now your thermometer is ready to go!