Boiling point calibration tests are trickier than ice bath tests and are unnecessary if an ice bath test proves conclusive. Water boils at 212°F at sea level, but only at sea level. Changes in atmospheric pressure at elevations above or below sea level alter the temperature at which water boils. For example, water typically boils at 202°F in Denver, CO.
Fortunately, finding the boiling point where you live is easy. Check out our simple boiling point calculator to find out at what temperature water boils where you are. Once you’ve got that info, you’re ready to begin your boiling point calibration test.
Fill a saucepan or pot at least four inches deep with clean water.
(Note: impurities or salt can significantly affect the boiling temperature of water.)
Place the pot on the stove and turn the burner on high. (Do NOT use the microwave.)
Wait until the water comes to a strong, rolling boil that does not stop with stirring.
As soon as the water reaches a boiling point, put the tip of the thermometer probe a few inches into the water until the water temperature stabilizes. (Note: Be careful to keep your probe in the center of the pot and off of the bottom of the pot. If the tip comes in contact with the side, or bottom of the pot it will show a higher temperature.)
Cross-check the temperature reading with the boiling point in your area and you’ll have a good indication if your thermometer is reading temperatures correctly. If the thermometer needs adjusting, follow the guidelines set forth by the manufacturer. However, before you attempt to adjust a digital, instant-read thermometer, check that the readings are within the manufacture’s accuracy specifications. (Look for the ±°F on the documentation that came with your thermometer.) If it’s within the specified tolerance, don’t adjust.