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Boiling point by elevation

A field rule for water that boils cooler up high

Water boils at a lower temperature as air pressure drops. A field rule used by camp cooks is about 1 °F lower for every 500 feet above sea level, which is about 1 °C for every 300 meters. This page applies that rule. It is not a thermometer, and weather pressure moves the real boil.

Inputs

Result

Fill in the fields and press Calculate.

Disclaimer: A camp rule of thumb. Confirm with a thermometer if the temperature matters.

How to use

  1. Enter the elevation of camp and choose feet or meters.
  2. Press Calculate. The hero is degrees Fahrenheit.
  3. The Celsius line uses the same drop. The drop line shows how far this is below a sea-level boil.
  4. Add time to the cook, not a hotter flame, when the temperature is lower. The page does not tell you how many extra minutes a recipe needs.

How it's calculated

In feet, the drop is elevation ÷ 500, in degrees Fahrenheit. Boiling point = 212 − that drop. Celsius = 100 − (drop ÷ 1.8).

In meters, the drop is elevation ÷ 300, in degrees Celsius. Fahrenheit = 212 − (that drop × 1.8). Sea level is the zero point of the rule.

Worked example

At 5,000 feet the drop is 10 °F, so the rule says water boils at 202 °F, about 94.4 °C. At 1,500 meters the drop is 5 °C, so the rule says 95 °C.

Assumptions

The field rule only. A high-pressure weather day or a storm changes the boil. The page does not read a barometer. Altitude sickness and hydration are not computed here.

FAQ

Is this the true boiling point?

It is the field rule printed above. A thermometer in the pot is the measurement. Weather pressure moves the result.

Why do recipes take longer?

Boiling water is cooler, so the food sits at a lower temperature. This page stops at the temperature. It does not adjust a cookbook.

What about a pressure cooker?

A sealed cooker raises the pressure on purpose. This rule is for an open pot.

Does elevation gain on the trail page do this?

No. Elevation gain adds climbs along a route. This page wants the elevation of the place you are cooking.

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