Dew Point Calculator
Calculate dew point from temperature and humidity using the Magnus formula. The dew point is the temperature water vapor condenses.
Inputs
Dew point
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In Celsius
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Comfort level
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Temperature spread
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Fog/dew likelihood
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About Dew Point Calculator
Dew point vs humidity
Relative humidity depends on temperature — 50% at 100°F holds far more water than 50% at 50°F. Dew point is absolute and more meaningful for comfort. Dew points above 65°F feel sticky regardless of RH.
How dew forms
When air cools to dew point, water vapor condenses. Grass radiates heat faster than air, so grass cools below air temp on clear nights — dew lands on grass first.
Pilot use
When air temp - dew point < 5°F, fog and low ceilings are likely. Pilots watch dew point spreads as carefully as visibility forecasts.