Dew Point Calculator
Calculate the temperature at which dew forms.
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Comfort Level: --
What is Dew Point?
The dew point is the temperature to which air must be cooled to become saturated with water vapor. When cooled further, the airborne water vapor condenses to form liquid water (dew). It provides a more absolute measure of how "humid" it feels than relative humidity does.
The Formula
We use the Magnus approximation (T in °C):
Td = (237.3 * B) / (1 - B)
Where B = (ln(RH/100) + (17.27*T)/(237.3+T)) / 17.27
Where B = (ln(RH/100) + (17.27*T)/(237.3+T)) / 17.27
Comfort Scale
- < 50°F (10°C): Dry / Comfortable
- 55-65°F (12-18°C): Sticky
- > 70°F (21°C): Oppressive / Muggy
FAQ
80% humidity at 40°F feels dry. 80% humidity at 90°F feels like a sauna. Dew
point strips away the temperature variable to show exactly how much moisture is in the air.