Vapour Pressure of Water Calculator

Vapour Pressure: -- kPa

How to Use This Calculator

Simply enter the temperature in Celsius in the input box above. The calculator will automatically compute the vapour pressure of water at that temperature.

What is this Calculator Used For?

This tool calculates the vapour pressure of water based on temperature using the Antoine equation. It is commonly used in chemistry and physics to understand phase transitions.

Formula Used

Antoine Equation:
log10(P) = A - (B / (C + T))
where:

  • P is the vapour pressure in mmHg
  • T is the temperature in °C
  • A = 8.07131, B = 1730.63, C = 233.426 (constants for water)

To convert mmHg to kPa: PkPa = PmmHg × 0.133322

Example

At 25°C:
log10(P) = 8.07131 - (1730.63 / (233.426 + 25)) = 1.283
P = 10^1.283 ≈ 19.2 mmHg ≈ 2.56 kPa