What is the boiling point of water and why does it change with pressure?

The boiling point of water is the temperature at which water transitions from a liquid to a gas (steam). At standard sea-level atmospheric pressure (1 atmosphere or 101.325 kPa), pure water boils at 100°C (212°F). However, the boiling point of water at different pressures varies significantly-understanding this relationship between boiling point water pressure is crucial for many applications.

The water boiling temperature at pressure changes because boiling occurs when the vapor pressure of the liquid equals the surrounding atmospheric pressure. At higher altitudes, atmospheric pressure is lower, so water boils at lower temperatures. For example, at the top of Mount Everest, water boils at approximately 68°C (154°F). In vacuum conditions, the boiling point water vacuum relationship becomes even more dramatic-water can boil at room temperature or below when pressure is sufficiently reduced. Conversely, in a pressure cooker or at lower elevations, increased pressure raises the boiling point, allowing food to cook faster.

Tool Description

This water boiling point calculator determines the boiling point of water at different pressures using the Antoine equation, a well-established thermodynamic formula. Whether you need to calculate the boiling point water pressure relationship for high-altitude cooking, laboratory work, or vacuum systems, this tool provides accurate results instantly. Simply input the pressure value, select your preferred pressure unit (atmospheres or bar), and choose your desired temperature unit (Celsius, Fahrenheit, or Kelvin).

Features

  • Multiple Pressure Units: Supports atmospheres (atm) and bar
  • Multiple Temperature Units: Display results in Celsius, Fahrenheit, or Kelvin
  • Wide Pressure Range: Accurate calculations from 0.006 to 10 atmospheres
  • Real-time Calculation: Instantly see boiling point changes as you adjust pressure
  • Scientific Accuracy: Uses the Antoine equation for precise thermodynamic calculations

Use Cases

  • High-Altitude Cooking: Understand why cooking times need adjustment at different elevations
  • Laboratory Work: Calculate precise boiling points for scientific experiments
  • Pressure Cooking: Understand the relationship between pressure and cooking temperature
  • Educational Purposes: Learn about thermodynamics and phase transitions
  • Industrial Applications: Design processes involving water evaporation or distillation
  • Weather and Aviation: Understand atmospheric pressure effects on water vapor

Conversion Details

The calculator uses the Antoine equation, which provides a mathematical relationship between vapor pressure and temperature:

log₁₀(P) = A - B/(C+T)

Where:

  • P is the vapor pressure in mmHg
  • T is the temperature in °C
  • A, B, C are substance-specific constants (for water: A=8.07131, B=1730.63, C=233.426)

The calculator automatically converts between different pressure units and temperature scales to provide accurate results in your preferred format.