Estimate saturation vapor pressure from temperature. This calculator shows the maximum water vapor pressure air can hold at a given temperature and converts the result into kPa, hPa, Pa, PSI, bar, atm, mmHg, and inHg.
Temperature:
Enter the air or surface temperature. Temperature is the main input used to estimate saturation vapor pressure.
Formula:
Choose Magnus, Tetens, or Buck formula. These are common approximation formulas for water vapor pressure.
Actual vapor pressure:
If you enter relative humidity, the calculator can also estimate actual vapor pressure as saturation pressure multiplied by relative humidity.
A saturation vapor pressure calculator is useful for weather, humidity, dew point, HVAC, greenhouses, drying, evaporation, agriculture, science lessons, and moisture calculations.
This calculator estimates saturation vapor pressure for water vapor. Real values can vary slightly depending on formula, surface type, and measurement conditions.
A common Magnus estimate over liquid water is:
eₛ = 0.61094 × exp((17.625 × T) / (T + 243.04))
Saturation vapor pressure is the maximum water vapor pressure possible at a given temperature before condensation begins.
Yes. Saturation vapor pressure increases rapidly as temperature rises, which is why warm air can hold more water vapor than cold air.
Using a common approximation over liquid water, saturation vapor pressure at 20°C is about 2.34 kPa, or about 23.4 hPa.
No. Saturation vapor pressure is the maximum possible value at a temperature. Actual vapor pressure depends on relative humidity.