Dial tips must penetrate about two inches of the food. The thermometer should penetrate the thickest part of the food. If a meat patty is not thick enough to check from the top, insert the thermometer in sideways. To check the thermometer calibration, place the stem in a cup of boiling water. If correct, it will read 212 degrees Fahrenheit.
Most thermometers have a calibration nut under the dial that can be adjusted.
Wash the thermometer after each use.