Dew Point Calculator

Calculate the dew point

The dew point is the temperature to which air must be cooled for its water vapour to condense into dew, and it is one of the best indicators of how humid and comfortable the air feels. This calculator uses the Magnus formula, taking the air temperature in Celsius and the relative humidity. At twenty-five degrees with sixty percent humidity, the dew point is about seventeen degrees. Unlike relative humidity, the dew point is an absolute measure, so it compares conditions fairly across different temperatures.

The higher the dew point, the more moisture is in the air and the more humid it feels.

Dew point and comfort

Meteorologists favour the dew point over relative humidity for describing comfort because it directly reflects the amount of moisture in the air. A dew point below ten degrees feels dry and pleasant, around sixteen it starts to feel humid, and above twenty-one it becomes oppressive and sticky. The dew point also tells you when condensation will form, which matters for windows, buildings and dew on surfaces.

Because it is an absolute measure, two places with the same dew point feel similarly humid even if their temperatures and relative humidities differ. The result is shown in Celsius and Fahrenheit. All calculation happens locally in your browser.

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