Dew Point Calculator
Calculate the dew point temperature from air temperature and relative humidity.
Result
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A dew point calculator determines the temperature at which air becomes saturated and water vapor begins to condense, based on temperature and humidity.
Examples
Summer day
Temperature: 85°F (29.4°C), Humidity: 65%. Dew Point = 71.6°F (22.0°C). Comfort level: Oppressive.
Comfortable day
Temperature: 75°F (23.9°C), Humidity: 40%. Dew Point = 49.6°F (9.8°C). Comfort level: Dry — pleasant.
Frequently Asked Questions
Why is dew point better than humidity for measuring comfort?
Relative humidity is relative to the current temperature — 50% RH at 95°F is far muggier than 50% RH at 65°F. Dew point measures the absolute moisture content, so a dew point of 70°F always feels oppressive regardless of the air temperature.
What causes condensation on windows?
Condensation forms when the surface temperature of the window drops below the dew point of the indoor air. This is common in winter when warm, moist indoor air meets cold glass.
Result
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Quick Tips
- •Dew point is a better indicator of comfort than relative humidity because it is absolute.
- •A dew point above 65°F (18°C) feels muggy to most people.
- •Pilots use the temperature-dew point spread to estimate cloud bases.
- •When the dew point equals the air temperature, the air is saturated (100% RH) and fog or dew forms.