Dew Point & Humidity Calculator
Calculate the dew point from air temperature and relative humidity — or relative humidity from temperature and dew point — with a comfort rating.
How to use
- 1Enter the air temperature.
- 2Enter the relative humidity (or the dew point to get humidity).
How it's calculated
Magnus formula: γ = ln(RH/100) + aT ÷ (b + T); dew point = bγ ÷ (a − γ), with a = 17.62 and b = 243.12 °C.
Frequently asked questions
What dew point feels comfortable?
Below about 55 °F (13 °C) feels dry and comfortable; 60–65 °F (16–18 °C) sticky; above 70 °F (21 °C) oppressive.
Why does condensation form on windows?
When a surface is colder than the dew point, water vapor condenses on it.
Is dew point better than relative humidity?
For comfort, often yes — relative humidity depends on temperature, while dew point measures the actual moisture in the air.