Boiling Point at Altitude Calculator

By Bogna Szyk
Last updated: Sep 23, 2021

This boiling point at altitude calculator can help you find the boiling point of water. Not surprisingly, the temperature at which water starts boiling is not constant and depends on pressure, which in turn is dependent on altitude. In this article, we will present you with the boiling point elevation equation and explain in detail how to calculate the boiling point of water at any altitude.

What is the boiling point?

It is simply the temperature at which water starts boiling — in other words, it changes its state from liquid to gas. This temperature is dependent on pressure and the substance type. Hence, you can be sure that each sample of clear water will start boiling at the same temperature at a given terrain elevation.

Boiling point of water at sea level

You don't have to use our boiling point at altitude calculator to determine the boiling point of water at sea level. It is always the same — 100 °C, or 212 °F. Actually, the formula for boiling point uses this value as the basis of calculations.

Similarly, the freezing point of water at sea level is a constant value — 0 °C or 32 °F.

Boiling point elevation equation

Remember that the boiling point of water depends solely on pressure. This boiling point calculator finds the pressure at altitude assuming that the pressure at sea level is constant and equal to 1013 hPa (1.013 bar). This approximation is sufficient for this kind of calculations. If you want to find more precise results, check out our air pressure at altitude calculator.

The formulas for boiling point are:

boiling point = 49.161 * ln(pressure) + 44.932

pressure = 29.921 * (1 - 0.0000068753 * altitude)^ 5.2559

Note that these formulas use specific units:

  • boiling point is in degrees Fahrenheit (°F);
  • pressure is expressed in inches of mercury (inHg); and
  • altitude should be put into the equation in the imperial unit — feet (ft).

However, when using this boiling point at altitude calculator, you can use a wide range of units for each variable.

How to calculate the boiling point

Let's assume you went on a hiking trip to Machu Picchu. You wonder what temperature you will need to boil water there. Let's calculate it…

  1. Check the altitude at Machu Picchu (before your departure to Peru). It is located at 2430 meters (7970 ft) above sea level.

  2. Input this altitude (in imperial unit) to the formula for pressure:

    pressure = 29.921 * (1 - 0.0000068753 * 7970)^ 5.2559 = 22.25 inHg

  3. Now, input this pressure into the boiling point equation:

    boiling point = 49.161 * ln(22.25) + 44.932 = 197.44°F

  4. Congratulations! Now you know the boiling point of water at Machu Picchu.

Bogna Szyk
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