Boiling Water Test
The most common way to test a thermometer is to place it in boiling water. An accurate thermometer will read about 212*F in boiling water at sea level under normal atmospheric conditions.
To test your thermometer, bring a pot of water to a vigorous boil. Hold the thermometer stem or probe in the water, making sure not to touch the sides or bottom of the pot, and take your reading.
Remember that there are several factors that affect the boiling point of water:
*As atmospheric pressure decreases, the boiling point decreases. Atmospheric pressure will vary depending on your altitude and local weather conditions.
*Hard water boils at a temperature 1-2*F higher than soft water, due to dissolved mineral salts.
*Using a tall, narrow pot will result in a boiling point about 1*F higher than a short, wide pot.
If you live at high altitude, you'll need to take that into account when testing your thermometer. The table below lists the approximate boiling point for a number of different altitudes. As a general rule, the boiling point decreases approximately 1.8*F for every 1000-foot increase in altitude. Note that the actual boiling point may be higher or lower depending upon atmospheric pressure in your area on any given day.
AltitudeBoiling Point (F/C)
Another way to determine your boiling point is to use a Boiling Point Calculator
. By entering your current barometric pressure and your elevation, you can get a good estimate of your boiling point.