Dew Point & Humidity Calculator

Compute the dew point, saturation and actual vapor pressure, absolute humidity, and wet-bulb temperature from a temperature and relative humidity. The dew point uses the Magnus equation; vapor pressure uses the August–Roche–Magnus relation; absolute humidity and the wet-bulb follow standard meteorological formulas. Pairs with the Apparent Temperature tool. Everything runs locally in your browser.

Temperature Relative humidity %

Enter a temperature and humidity.

Dew point (Magnus, Alden/Murray constants): α = ln(RH/100) + 17.625·T/(243.04+T), then Td = 243.04·α / (17.625 − α) in °C. Saturation vapor pressure e_s = 6.1094·e^{17.625·T/(243.04+T)} hPa; actual vapor pressure e = (RH/100)·e_s. Absolute humidity AH = 216.7·e / (T+273.15) g/m³. Wet-bulb uses the Stull (2011) empirical formula, valid roughly for 5–99% RH and 5–99 °C; outside that range it is marked as approximate. Everything runs locally — nothing leaves your browser.