Estimate saturation vapor pressure and actual vapor pressure from temperature and relative humidity. This calculator converts vapor pressure into kPa, hPa, Pa, PSI, bar, atm, mmHg, and inHg.
Temperature:
Temperature determines the saturation vapor pressure, or the maximum water vapor pressure air can hold at that temperature.
Relative humidity:
Relative humidity tells what percent of the saturation vapor pressure is currently present.
Actual vapor pressure:
The calculator multiplies saturation vapor pressure by relative humidity to estimate actual vapor pressure.
A vapor pressure calculator is useful for weather, humidity, dew point, HVAC, drying, greenhouses, agriculture, science lessons, evaporation estimates, and air moisture calculations.
This calculator estimates water vapor pressure in air. Actual measurements can vary with local weather, sensors, and conditions.
A common saturation vapor pressure estimate is:
eₛ = 0.61094 × exp((17.625 × T) / (T + 243.04))
Then actual vapor pressure is:
e = eₛ × RH ÷ 100
Vapor pressure is the pressure exerted by water vapor in the air. In weather and humidity calculations, it describes how much water vapor is present or possible at a temperature.
Saturation vapor pressure is the maximum vapor pressure possible at a given temperature before condensation begins.
Calculate saturation vapor pressure from temperature, then multiply it by relative humidity divided by 100.
Yes. Saturation vapor pressure increases rapidly as temperature rises, which is why warm air can hold more water vapor than cold air.