Boiling Point Altitude Calculator
Water boiling point from elevation.
What it does
Water boils when vapor pressure beats air pressure, and thin mountain air surrenders early: Denver simmers near 95 C while sea level holds 100. Cooking times stretch with every lost degree.
The tool above takes elevation in meters or feet. It returns boiling Celsius and Fahrenheit with the gap below sea level.
The default 1500 m boils at 95 C, or 203 F, five below the mark. The 3000 m case reads 90 C, and 10,000 ft reads 89.8 C.
Water science texts tie boiling to ambient pressure with elevation, and chemistry references walk the same vapor curves. The 1 C per 300 m line fits observed towns within fractions.
Lower boils never lower kill temperatures: thermometers still rule poultry and preserves. Stretch pasta minutes, shift candy stages down by the gap, or pressure cook back to speed.
How to use
- Pick meters or feet.
- Type the elevation.
- Read Celsius first.
- Read Fahrenheit beside it.
- Read the gap last.
- Add cook minutes.
Formula
- alt
- Elevation in m or ft.
- C
- Boiling point in Celsius.
- drop
- Gap below the 100 C sea mark.
USGS water science and LibreTexts chemistry frame boiling as vapor pressure meeting ambient pressure, falling with elevation. The 1 C per 300 m linearization matches observed points from Denver to 3000 m within fractions. Fahrenheit converts from the Celsius result, so both systems agree exactly.
Worked example
Example: mile high town
Metric defaults: 1500 m.
- Town: 1500 m elevation.
- Drop: 1500 / 300 = 5 C below sea level.
- Boil: 100 minus 5 = 95 C.
- F: 95 x 9/5 + 32 = 203 F.
- Mirror: 4921 ft converts to the same 95 C.
- Tool shows 95 C, 203 F, 5 C below sea level.
Reference table
| Elevation | Boils | Gap |
|---|---|---|
| Sea level | 100 C | 0 |
| 1500 m | 95 C | 5 C |
| 3000 m | 90 C | 10 C |
| 10,000 ft | 89.8 C | 10.2 C |
Limits
- Linear rule to 9000 m.
- Water only.
- Weather pressure unread.
- Pasta rules of thumb apart.
Common mistakes
- Timing pasta by sea clocks.
- Trusting rolling looks alone.
- Shifting safe temps down.
- Ignoring candy stage gaps.
- Extrapolating past Everest.
Try it yourself
Quick checks. Answers sit tucked under each question.
3000 m?
90 C with 194 F, 10 below sea level.
10,000 ft?
89.8 C with 193.7 F.
Minus 400 m?
Below sea level is out of range: enter altitude from 0 up.
Questions
Drop rate?
About 1 C per 300 m, or 1 F per 540 ft. Denver near 95 C and 203 F.
Why lower?
Lower air pressure lets bubbles form easier. Vapor pressure meets ambient sooner.
Cooking longer?
Yes, add minutes to pasta, rice, and eggs. Pressure cookers restore sea level speed.
Safe temps shift?
No, kill temperatures stay: thermometers rule regardless of the boil reading.
Candy stages?
Candy stages drop with the boil: subtract the same gap from every stage.
Very high?
Linear rules fade past Everest zones; mountaineers correct further.
Other liquids?
No, this covers water. Other liquids carry their own vapor curves.