GlenCalc

Dew point calculator

The dew point is the temperature to which air must cool for dew to form. It is a better measure of how muggy it feels than relative humidity.

Your answer

Dew point64.3 °FGetting sticky

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How we worked it out

Updated as you change the numbers.

  1. Magnus formula: γ = ln(RH/100) + aT ÷ (b + T); dew point = bγ ÷ (a − γ), with T in °C, a = 17.625, b = 243.04 °C.

Method and assumptions

The Magnus approximation with Alduchov and Eskridge’s coefficients is accurate to about 0.1 °C between −40 °C and 50 °C.

Questions

What is the dew point at 77 °F and 65% humidity?

About 64 °F: getting sticky.

Sources

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