GlenCalc

Wet bulb temperature calculator

Wet bulb temperature is how cool a wet surface can get by evaporation. It matters for heat stress and for evaporative (swamp) coolers.

Your answer

Wet bulb temperature72.1 °F
Wet bulb depressionHow much evaporation can cool the air7.7 °C

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How we worked it out

Updated as you change the numbers.

  1. Stull (2011): Tw = T·atan(0.151977·√(RH + 8.313659)) + atan(T + RH) − atan(RH − 1.676331) + 0.00391838·RH^1.5·atan(0.023101·RH) − 4.686035, in °C.

Method and assumptions

Stull’s empirical formula, accurate to within about 1 °C at sea-level pressure. It is not the wet bulb globe temperature (WBGT), which also counts sun and wind.

Questions

What is the wet bulb temperature at 86 °F and 50% humidity?

About 72.1 °F (22.3 °C).

Sources

Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.

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