Saturation Vapor Pressure Calculator

About this calculator

The Tetens formula, a widely used empirical approximation published by Otto Tetens in 1930, estimates the saturation vapor pressure of water over a flat surface from air temperature alone — the maximum partial pressure water vapor can exert at that temperature before it begins to condense. Saturation vapor pressure rises roughly exponentially with temperature, which is why warm air can hold dramatically more moisture than cold air.

Meteorologists and atmospheric scientists use saturation vapor pressure as the foundation for calculating relative humidity, dew point, and the vapor pressure deficit that drives evaporation and plant transpiration; agronomists and greenhouse managers rely on the same relationship to estimate crop water demand, while HVAC engineers use it in psychrometric calculations for dehumidification and condensation control.

This calculator takes an air temperature and applies the Tetens formula to return the saturation vapor pressure at that temperature.