Boiling Point at Altitude Calculator

Why Does Boiling Point Change with Altitude?

The boiling point of water decreases as altitude increases because atmospheric pressure decreases at higher elevations. At sea level, where atmospheric pressure is 1 atm (101.325 kPa), water boils at 100 °C (212 °F). However, at higher altitudes, the lower pressure means water molecules need less energy to escape into vapor, so boiling occurs at a lower temperature.

This phenomenon has practical implications for cooking, food preparation, and industrial processes at high elevations. For example, at 2,000 meters above sea level, water boils at approximately 94 °C, which means food takes longer to cook and certain chemical reactions proceed more slowly.

How the Calculation Works

Our calculator uses two steps to determine the boiling point at any altitude:

Step 1: Calculate atmospheric pressure at altitude using the barometric formula:

$$P = P_0 \cdot \left(1 - \frac{L \cdot h}{T_0}\right)^{\frac{g \cdot M}{R \cdot L}}$$

Where:

• $P_0$ is sea level standard atmospheric pressure (101325 Pa)
• $L$ is the temperature lapse rate (0.0065 K/m)
• $h$ is the altitude above sea level
• $T_0$ is sea level standard temperature (288.15 K)
• $g$ is gravitational acceleration (9.80665 m/s²)
• $M$ is molar mass of Earth's air (0.0289644 kg/mol)
• $R$ is the universal gas constant (8.314 J/(K·mol))

Step 2: Calculate the boiling point at that pressure using the Clausius-Clapeyron equation:

$$T_b = \frac{1}{\frac{1}{T_0} + \frac{R}{\Delta H} \cdot \ln\left(\frac{P_0}{P}\right)}$$

where $\Delta H$ is the latent heat of vaporization of water (40,660 J/mol) and $T_0$ is the boiling point at sea level (373.15 K).

Boiling Point of Water at Common Altitudes

Explore related thermodynamics tools like the Boiling Point Calculator, the Boiling Point Elevation Calculator, and the Pressure Converter.