Dew Point Calculator

The dew point is the temperature to which air must be cooled for water vapour to condense. Unlike relative humidity, dew point is an absolute moisture measure that stays constant when temperature changes

The calculator uses the standard published formula for dew point. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, Celsius. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Uses the Magnus formula: alpha = ln(RH/100) + (a × T)/(b + T). Each step in the calculation is shown so you can verify the result manually.