Boiling Point at Altitude Calculator
Enter your altitude to estimate the atmospheric pressure there and the temperature at which pure water boils. The calculator uses the standard-atmosphere pressure model, and you can enter the current sea-level pressure to account for the weather.
Last updated: September 26, 2026
Frequently asked questions
Why does water boil at a lower temperature at altitude?
Air pressure drops with height, and water boils when its vapor pressure equals the surrounding pressure, so the boiling temperature falls.
How much does the boiling point drop per 1,000 m?
Roughly 3 °C per 1,000 m near sea level, but the relationship is slightly curved, which is why this calculator uses a pressure model rather than a straight line.
Why can I enter the sea-level pressure?
Weather changes the local pressure by several kPa. Entering the current pressure reduced to sea level makes the estimate more realistic than the standard value.
Is the result exact?
No. It assumes the standard atmosphere and pure water in an open container. Local conditions and dissolved substances shift the boiling point.
What about a pressure cooker?
A sealed vessel has its own internal pressure, so altitude alone does not give its boiling temperature. Use the Boiling Point Calculator with the actual absolute pressure.
What altitude range does it cover?
From -500 m to 11,000 m, the lower part of the standard atmosphere. Outside this range the model is not used.