How to use the boiling point at altitude calculator
- Enter your elevation and pick feet or meters. Negative values work for places below sea level, down to a limit.
- To use a real reading instead of a standard atmosphere, open More options and enter the local air pressure in inches of mercury. Use the station pressure from a barometer, not the sea-level figure in a forecast.
- Read the boiling point in Fahrenheit and Celsius, how far it is below sea level, the pressure used and a table for other elevations.
- Copy the result or print it for your kitchen notes.
Formula
Pressure = 101325 x (1 - 2.25577e-5 x height in meters)^5.25588 pascals
Boiling point = 1730.63 / (8.07131 - log10(pressure in mmHg)) - 233.426 degrees C
Fahrenheit = Celsius x 9 / 5 + 32
The first line is the standard atmosphere for the lower part of the sky, and the second is the Antoine equation for water. As a cross-check, the Clausius-Clapeyron equation with 40.66 kJ/mol agrees to within about a quarter of a degree up to 10,000 feet.
A kitchen at 5,280 feet
At 5,280 feet (1,609 m) the standard air pressure is about 83,428 pascals, 24.64 inches of mercury, or 82.3 percent of sea level. Water boils at 94.7 C, which is 202.4 F, about 9.6 F below the 212 F you get at sea level.
At 2,000 feet it boils at 208.4 F (98.0 C), at 8,000 feet at 197.4 F (91.9 C), and at 10,000 feet at 193.8 F (89.9 C). On the summit of a 29,000 foot peak it is 158.5 F (70.3 C). A barometer reading of 24.9 inHg gives 202.9 F (94.9 C), and 1,500 meters gives 203.0 F (95.0 C).
Why water boils at a lower temperature up high
Water boils when its vapor pressure equals the pressure of the air above it. Higher up there is less air, so the pressure is lower and the water reaches that point at a lower temperature. Each thousand feet lowers the boiling point by roughly two Fahrenheit degrees, which is why pasta, beans and eggs can take longer and why some recipes have a high-altitude version.
Weather also matters. A passing storm can lower the pressure and the boiling point by about a degree, and salt or sugar dissolved in the pot raises it a little. For temperature and unit changes in the kitchen, the Cooking Measurement Converter is a useful companion, and the Unit Converter handles pressure and length.
What the boiling point does not tell you
A lower boiling point means food in boiling water cooks at a lower temperature, so times go up. But baking, canning and candy making depend on more than the boiling point: leavening, evaporation, oven air pressure and safety rules for preserving food all change with elevation. Use recipes and guides written for your elevation, and do not rely on this page for processing times or safe canning. To adjust an oven setting, the Convection Oven Conversion Calculator and the Cooking Time by Weight Calculator are good next steps.
Assumptions and limits
- Without a pressure reading, the tool uses the standard atmosphere, which approximates average conditions at each elevation.
- The water is pure. Dissolved salt or sugar changes the boiling point slightly.
- Elevation can be from -1,500 to 30,000 feet, or -450 to 9,000 meters.
- Everything is calculated in your browser.
Frequently asked questions
At what temperature does water boil at 5,000 feet?
About 202 to 203 F, or 95 C. At 5,280 feet it is 202.4 F (94.7 C) with a standard atmosphere. Your real value moves a little with the weather.
How much does the boiling point drop for each 1,000 feet?
About 2 F, or a little over 1 C, in the range most people live in. The table on the page shows the values at several elevations.
Why enter the air pressure myself?
The standard atmosphere is an average. If you have a barometer, enter the pressure at your location for that day, as station pressure, and the tool will give a more exact result.
Does a lower boiling point change cooking times?
Yes, food cooks more slowly in water that boils at a lower temperature. How much more depends on the food, so follow a recipe written for your elevation.