Free Dew Point Calculator

Find the dew point temperature from air temperature and humidity.

Dew point is often considered a better indicator of how humid it actually "feels" than relative humidity alone, since relative humidity is temperature-dependent while dew point directly reflects the amount of moisture in the air. Above 65°F dew point starts feeling muggy; above 70°F feels oppressive to most people.

Worked Example

Example: 85°F air temperature, 55% relative humidity → dew point ≈ 67°F (moderately muggy).

Formula / Method

Magnus formula: γ = ln(RH/100) + (17.625×T)/(243.04+T), then Dew Point = 243.04×γ / (17.625−γ), computed in Celsius then converted to °F.

Worked Example

Example: 85°F air temperature, 55% relative humidity → dew point ≈ 67°F (moderately muggy).

Formula / Method

Magnus formula: γ = ln(RH/100) + (17.625×T)/(243.04+T), then Dew Point = 243.04×γ / (17.625−γ), computed in Celsius then converted to °F.