Physics

Relative Humidity Calculator

Find relative humidity from temperature and dew point.

Calculated Output

Relative humidity (%) 53.849

Formula: RH = 100·e(T_d) ÷ e(T)

Step-by-Step Breakdown

1. Values used:

2. Air temperature = 25 °C

3. Dew point = 15 °C

5. Relative humidity = 53.849%

Did this calculator solve your problem today?

The math behind it

RH = 100 × (vapour pressure at dew point) ÷ (saturation vapour pressure at air temperature).

25 °C with a 15 °C dew point → about 54% RH.

When is RH 100%?

When the dew point equals the air temperature — the air is saturated.