The boiling point of water is 212°F (100°C) at sea level. The U.S. Geological Survey puts it simply: water “boils at 212 °F (100 °C) at sea level. However, the boiling point decreases at higher altitudes.” Higher up, there is less air pressing down on the water, so it boils at a lower temperature. In Denver it boils at about 202°F; on top of Mount Everest, at about 160°F.
Below is a chart by altitude, the reason it changes, and the practical part: how long to boil water to make it safe to drink, which is a different question from what temperature it boils at.
Boiling point of water by altitude
These are approximate values for pure water. Weather changes air pressure a little from day to day, so treat them as a guide, not a lab figure. A handy rule: the boiling point drops roughly 1°F for every 500 feet you climb.
| Elevation | Example | Boiling point |
|---|---|---|
| Sea level (0 ft) | New York, Miami | 212°F (100°C) |
| 2,500 ft (760 m) | Some foothill towns | about 207°F (97°C) |
| 5,280 ft (1,610 m) | Denver | about 202°F (94°C) |
| 7,500 ft (2,290 m) | Mountain resort towns | about 198°F (92°C) |
| 10,000 ft (3,050 m) | High mountain passes | about 194°F (90°C) |
| 29,032 ft (8,849 m) | Summit of Mount Everest | about 160°F (71°C) |
Why does water boil at a lower temperature at altitude?
Water boils when its vapor pressure, the push of water molecules escaping as steam, matches the pressure of the air above it. At sea level that happens at 212°F. As you go up, the air gets thinner and pushes down less, so the water reaches that point at a lower temperature.
The flip side is why pressure cookers work. Sealing the pot raises the pressure inside, so the water has to get hotter before it boils, about 250°F (121°C) at roughly 15 psi above normal air pressure. Hotter water cooks food faster, which is why pressure cookers are popular at high altitude.
What temperature does water boil in Fahrenheit and Celsius?
212°F, which is 100°C, at sea level. The Celsius scale was built around water: 0°C is where it freezes and 100°C is where it boils at normal sea-level pressure. The USGS gives the matching freezing point as “32° Fahrenheit (°F) (0° Celsius).”
Does adding salt change the boiling point?
Yes, but only slightly in a kitchen. Anything dissolved in water raises its boiling point a little. The amount of salt in a pot of pasta water changes it by a fraction of a degree, so salt is for flavor, not for cooking faster.
How long should you boil water to make it safe?
This is the question that matters during a boil water notice. The CDC says: “Bring water to a full rolling boil for 1 minute.” At altitude it says, “If you are at an elevation above 6,500 feet, boil water for 3 minutes,” because water boils at a lower temperature up there.
The CDC calls boiling “the best method to kill disease-causing organisms, including viruses, bacteria, and parasites.” It does not remove chemicals, though. Lead, nitrate or PFAS stay in the water, and boiling concentrates them slightly as water evaporates. Our guide to how boiling makes water safe to drink covers what boiling does and does not fix, and does boiling remove chlorine or fluoride answers the two questions people ask most.
Is hotter boiling water better for tea and coffee?
At sea level you cannot get an open pot of water hotter than 212°F; once it boils, more heat just makes more steam. At altitude, the lower boiling point is why some people find their tea or coffee tastes weaker. Our guide to the best water for coffee and tea covers the minerals that matter more than a degree or two of temperature.
Frequently asked questions
What is the boiling point of water in Fahrenheit?
212°F at sea level. It is lower at higher altitudes, about 202°F in Denver.
What is the boiling point of water in Celsius?
100°C at sea level, by definition of the Celsius scale at standard pressure.
Why does water boil faster at high altitude?
It reaches its boiling point sooner because the boiling point is lower, but the water is not as hot. That is why food takes longer to cook at altitude.
Does boiling water kill all bacteria?
The CDC calls boiling the best method to kill disease-causing organisms, including viruses, bacteria and parasites. Boil for 1 minute, or 3 minutes above 6,500 feet.
Can water get hotter than 212°F?
Yes, under pressure. A pressure cooker raises it to about 250°F, and water can briefly superheat in a microwave in a very smooth container.
Does salt make water boil faster?
No. Salt raises the boiling point slightly, so in theory it takes a little longer to boil. The difference is too small to notice in a kitchen.
Sources
- U.S. Geological Survey, Water Science School: Facts About Water (General Information Product 219).
- U.S. Centers for Disease Control and Prevention, Water Disinfection for Travelers.
