Boiling Point at Altitude Calculator
The temperature water boils at for a given elevation — lower air pressure, lower boiling point, longer cooking.
Air pressure falls with height (the barometric formula gives about 84.
How the boiling point at altitude calculator works
Air pressure falls with height (the barometric formula gives about 84.6 kPa at 1,500 m against 101.3 at sea level), and water boils when its vapour pressure equals the air pressure. The Antoine equation turns that pressure back into a temperature: roughly 1 °C lower for every 300 m. Food cooks by temperature, so pasta, eggs and stews take longer at altitude and pressure cookers earn their keep.
Formula: P = 101.325 × (1 − 2.25577×10⁻⁵ h)^5.25588 kPa; T = 1730.63 ÷ (8.07131 − log₁₀ P(mmHg)) − 233.426
Worked examples
| Inputs | Water boils at | Note |
|---|---|---|
| Sea level | 100 °C | 100.0 °C |
| 1,500 m | 95 °C | about 95 °C |
| Denver, 5,280 ft | 94.7 °C | about 94.7 °C (202 °F) |
FAQFrequently asked questions
How much longer does food take at altitude?
As a rule, add 5–10% to boiling times for every 300 m; pulses and rice are the worst affected. Baking needs recipe changes — less leavening, more liquid — rather than just more time.
Why does water boil cooler at altitude?
Boiling happens when the water’s vapour pressure equals the air pressure above it. Air pressure falls with height, so the vapour pressure needed — and the temperature that produces it — falls too.
Does a pressure cooker fix it?
Yes — it raises the pressure inside by about one atmosphere, taking the boiling point to about 120 °C at sea level and around 116 °C at 2,000 m, which is why it is standard kit in mountain kitchens.
How accurate is this?
Within about half a degree in normal weather; a strong high- or low-pressure system shifts the boiling point by up to a degree either way.
Where these figures come from
- IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
- NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
- NIST Chemistry WebBook — thermochemical data
- Royal Society of Chemistry — the UK chemistry professional body
Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.