Water boils at 100.0 °C at sea level but at about 95.0 °C at 1,500 m; at 5,000 ft it boils near 202.9 °F.
| Altitude (m) | Air pressure (kPa) | Water boils at (°C) | Water boils at (°F) |
|---|---|---|---|
| 0 | 101.3 | 100.0 | 212.0 |
| 250 | 98.4 | 99.2 | 210.5 |
| 500 | 95.5 | 98.3 | 209.0 |
| 750 | 92.6 | 97.5 | 207.5 |
| 1,000 | 89.9 | 96.7 | 206.0 |
| 1,250 | 87.2 | 95.9 | 204.5 |
| 1,500 | 84.6 | 95.0 | 203.0 |
| 1,750 | 82.0 | 94.2 | 201.5 |
| 2,000 | 79.5 | 93.4 | 200.1 |
| 2,250 | 77.1 | 92.5 | 198.6 |
| 2,500 | 74.7 | 91.7 | 197.1 |
| 2,750 | 72.4 | 90.9 | 195.6 |
| 3,000 | 70.1 | 90.0 | 194.1 |
| 3,250 | 67.9 | 89.2 | 192.6 |
| 3,500 | 65.8 | 88.4 | 191.0 |
| 3,750 | 63.7 | 87.5 | 189.5 |
| 4,000 | 61.6 | 86.7 | 188.0 |
| 4,250 | 59.7 | 85.8 | 186.5 |
| 4,500 | 57.7 | 85.0 | 185.0 |
| 4,750 | 55.8 | 84.2 | 183.5 |
| 5,000 | 54.0 | 83.3 | 182.0 |
How it is computed
Air pressure comes from the standard-atmosphere barometric formula, P = 101.325 × (1 − 2.25577 × 10⁻⁵ × h)^5.25588 kPa. The boiling point is the temperature at which water's vapour pressure (Antoine equation) equals that pressure. Weather can move it by about 1 °C.
FAQ
Why does food take longer to cook at altitude?+
Boiling water is cooler up high, so pasta, rice and eggs cook more slowly; add time or use a pressure cooker.
What about the 1 °C per 300 m rule?+
It is the quick rule of thumb the calculator uses; it stays within a few tenths of a degree of this table up to about 3,000 m.