Boiling Point at Altitude Calculator

m
kPa
Chemistry

Find the boiling point of water at altitude or a given atmospheric pressure. Enter your altitude (or pressure) to see how much lower water boils as you climb — useful for cooking and brewing at elevation.

Formula

Tb ≈ 100 - 0.34 × (P_sea_level - P_actual), pressure decreases with altitude
  • Boiling Point at Altitude Calculator gives you a fast estimate using your inputs and updates instantly when you change any value.
  • Formula: Tb ≈ 100 - 0.34 × (P_sea_level - P_actual), pressure decreases with altitude
  • Input definitions: • Altitude: the numeric altitude used in the calculation • Or specify atmospheric pressure: the numeric or specify atmospheric pressure used in the calculation
  • Manual method: write down each input, apply the formula step by step, then compare your manual result with the calculator output.
  • Uses standard SI and chemistry units (mol, L, g/mol, M, Pa, K) unless otherwise stated.
  • Based on standard stoichiometric and thermodynamic equations. Results may vary with temperature, pressure, and substance purity.
  • Cross-check results against known standards or reference tables to confirm they are physically reasonable.
  • Practical tip: test a low, medium, and high scenario to understand sensitivity before making decisions.

Example Calculation

Inputs
  • Altitude: 0 m
  • Or specify atmospheric pressure: 101.325 kPa

Suppose you enter: Altitude = 0, Or specify atmospheric pressure = 101.325. The calculator applies the formula (Tb ≈ 100 - 0.34 × (P_sea_level - P_actual), pressure decreases with altitude) and shows all output values below. Change any input field to immediately see how the result changes.

Frequently asked questions

Why does water boil at a lower temperature at altitude?
Higher up, atmospheric pressure is lower, so water needs less heat for its vapor pressure to match the surrounding pressure and boil.
How much does boiling point drop with altitude?
Roughly 1 °C for every 300 m of elevation gain, so on a high mountain water can boil well below 100 °C.
Why does food take longer to cook at altitude?
Lower boiling temperatures mean water is cooler while boiling, so foods like pasta, rice, and eggs need more time.
Can I enter pressure instead of altitude?
Yes. Leave altitude at zero and set the atmospheric pressure directly to find the boiling point for that pressure.
Does this work for liquids other than water?
The estimates here are tuned for water. Other liquids have different vapor-pressure curves and boiling points.