Boiling point altitude calculator
This boiling point altitude calculator shows the temperature at which water boils at your elevation or at a measured air pressure. At sea level water boils at 212 °F (100 °C); at 5,000 ft the standard air pressure is 843 hPa and water boils at 202.9 °F (94.9 °C). That is about 1.8 °F less for every 1,000 ft.
Example: Calculate from: elevation · Units: feet, inHg · Elevation above sea level 5,000 → Water boils at: 202.9 °F (94.9 °C). Source: NIST Chemistry WebBook, SRD 69 – Water: Antoine equation parameters, 344–373 K (Bridgeman and Aldrich 1964; read 09.10.2026). Updated: .
How it is calculated
Water boils when its vapor pressure equals the air pressure. Higher up, the air pressure is lower, so water boils at a lower temperature. The calculator takes the standard air pressure for your elevation from the National Weather Service formula and then the boiling point from the Antoine equation for water published in the NIST Chemistry WebBook.
Boiling point of water by altitude
| Elevation | Air pressure | Boiling point |
|---|---|---|
| sea level | 29.92 inHg | 212.0 °F (100.0 °C) |
| 1,000 ft | 28.86 inHg | 210.2 °F |
| 2,000 ft | 27.82 inHg | 208.4 °F |
| 5,000 ft | 24.89 inHg | 202.9 °F (94.9 °C) |
| 7,500 ft | 22.65 inHg | 198.3 °F |
| 10,000 ft | 20.57 inHg | 193.7 °F (89.8 °C) |
| 14,000 ft | 17.57 inHg | 186.3 °F |
Formulas
Air pressure (NWS, standard atmosphere): p = 1013.25 hPa × (1 − hft ÷ 145,366.45)1 ÷ 0.190284. Boiling point (NIST, Antoine parameters by Bridgeman and Aldrich for 344–373 K): T = 1663.125 ÷ (5.08354 − log10(p in bar)) + 45.622 K. At 1013.25 hPa this gives exactly 100.00 °C.
Examples
- 5,000 ft: 843.0 hPa, water boils at 202.9 °F (94.9 °C).
- 1,000 m: 898.7 hPa, 96.7 °C.
- 3,000 m: 701.0 hPa, 90.0 °C.
- Mount Everest, 8,849 m: about 314 hPa in the standard atmosphere, 70.2 °C (158.3 °F).
- Dead Sea shore, −430 m: 1066 hPa, 101.4 °C.
Cooking at altitude takes longer because the water is cooler – the egg boiling time calculator accounts for elevation. Convert temperatures with the Fahrenheit to Celsius converter.
Limits
The standard atmosphere is an average: on a stormy day the pressure at your place can be 10–20 hPa lower, which lowers the boiling point by roughly 0.3–0.6 °C. For an exact value enter the station pressure measured where you are. The Antoine parameters are fitted for 71–100 °C; above sea level pressure or on the highest summits the equation is slightly extrapolated.
Frequently asked questions
At what temperature does water boil at 5,000 feet?
At about 202.9 °F (94.9 °C) in the standard atmosphere – 9.1 °F below the 212 °F at sea level.
How much does the boiling point drop with altitude?
About 1.8 °F per 1,000 ft, or about 1 °C per 300 m, in the range people live and hike in.
What is the boiling point of water at 10,000 feet?
About 193.7 °F (89.8 °C) at a standard pressure of 20.57 inHg.
At what temperature does water boil on Mount Everest?
At about 70 °C (158 °F): the standard air pressure at 8,849 m is only about 314 hPa.
Why does food take longer to cook at high altitude?
Boiling water cannot get hotter than its boiling point. At 10,000 ft it is about 18 °F cooler than at sea level, so heat reaches the food more slowly.
Can I use the air pressure from the weather report?
Weather reports usually give pressure reduced to sea level. For the boiling point you need the actual station pressure at your location.
Sources and legal basis
- NIST Chemistry WebBook, SRD 69 – Water: Antoine equation parameters, 344–373 K (Bridgeman and Aldrich 1964; read 09.10.2026)
- National Weather Service (NOAA) – Pressure Altitude formula (read 09.10.2026)
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