Boiling Point at Altitude Calculator — Water at Any Elevation
Water boils below 100 °C at altitude because air pressure drops. Enter your elevation to find the exact boiling point using the ISA barometric formula and Clausius–Clapeyron equation.
m
205.91 °F • 369.77 K • -3.38 °C from sea level
- 1
Pressure at altitude (ISA barometric formula)
101 325 × (1 − 0.0065 × 1,000 ÷ 288.15)^5.256 = 89.874 kPaAtmospheric pressure falls with altitude following the ISA troposphere model. - 2
Boiling point in Kelvin (Clausius–Clapeyron)
1 ÷ (1/373.15 − (8.314/40 650) × ln(89.874 ÷ 101.325)) = 369.766 K - 3
Convert Kelvin to Celsius
369.766 − 273.15 = 96.62
How does this calculator work?
At altitude h metres, atmospheric pressure is P = 101 325 × (1 − 0.0065 h / 288.15)^5.256 Pa. The boiling point of water at that pressure is T = 1 / (1/373.15 − (R/ΔHvap) × ln(P/101 325)) K, where ΔHvap = 40 650 J/mol. Water boils at ~94 °C at 2 000 m, ~83 °C at 5 000 m, and ~70 °C near the Everest summit.
Formula
How this is calculated
As altitude increases, the weight of air above decreases, so atmospheric pressure falls. The International Standard Atmosphere (ISA) troposphere model (valid to ~11 km) describes this as P(h) = P₀ × (1 − L·h/T₀)^(g·M/R·L), where P₀ = 101 325 Pa, T₀ = 288.15 K, the lapse rate L = 0.0065 K/m, g = 9.80665 m/s², and M = 0.0289644 kg/mol is the molar mass of air.
Water boils when its vapour pressure equals the surrounding atmospheric pressure. As that pressure drops, the boiling point falls. The Clausius–Clapeyron equation gives the new boiling temperature from the pressure ratio: T₂ = 1 / (1/373.15 − (R/ΔHvap) × ln(P/101 325)), using ΔHvap = 40 650 J/mol for water and R = 8.314 J/(mol·K).
In practice this matters for cooking — pasta, eggs and potatoes require higher temperatures to cook properly, so high-altitude recipes call for longer times or pressure cookers. It also explains why water-cooled electronics and industrial processes must account for site elevation when designing cooling systems.
Frequently asked questions
Water boils at approximately 90 °C at around 3 000 m (about 10 000 ft) above sea level — roughly the elevation of a high Andean city. At Everest Base Camp (~5 364 m) the boiling point drops to about 83 °C.
Boiling water is cooler at altitude, so food cooks at a lower temperature. Proteins denature and starches gelatinise more slowly; a 3-minute egg at sea level may need 5 minutes at 3 000 m. A pressure cooker restores normal boiling-point conditions by raising pressure inside the pot.
No. The ISA barometric formula used here applies to the troposphere (0–11 km). Above the tropopause the temperature profile changes and the formula diverges from reality. For aviation or stratosphere problems, use the full ISA multi-layer model.
Also known as
TG we-Calculate Editorial Team. (2026). Boiling Point at Altitude Calculator — Water at Any Elevation [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/boiling-point-altitude-calculator
TG we-Calculate Editorial Team. "Boiling Point at Altitude Calculator — Water at Any Elevation." TG we-Calculate. 2026. https://we-calculate.com/calculator/boiling-point-altitude-calculator.
TG we-Calculate Editorial Team, "Boiling Point at Altitude Calculator — Water at Any Elevation," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/boiling-point-altitude-calculator
@misc{wecalculate_boiling_point_altitude_calculator, title = {Boiling Point at Altitude Calculator — Water at Any Elevation}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/boiling-point-altitude-calculator}}, year = {2026}, note = {TG we-Calculate} }
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