Estimate relative humidity using air temperature and dew point. This calculator shows humidity percentage, temperature-dew point spread, vapor pressure estimates, and a simple humidity comfort guide.
Air temperature:
Enter the current air temperature.
Dew point:
Enter the dew point temperature. Dew point must normally be equal to or lower than the air temperature.
Temperature unit:
You can enter both values in Fahrenheit or Celsius. The calculator converts as needed.
Relative humidity result:
The calculator estimates the percent of moisture in the air compared with the maximum amount possible at that temperature.
A relative humidity calculator is useful for weather planning, indoor comfort, HVAC checks, greenhouse monitoring, gardening, condensation risk, and understanding how dry or humid the air feels.
Humidity percentage changes with temperature, so the same dew point can produce different relative humidity values at different air temperatures.
Your result shows the estimated relative humidity percentage based on the air temperature and dew point. A higher percentage means the air is closer to saturation, while a lower percentage means the air is drier compared with how much moisture it could hold.
Relative humidity is the amount of water vapor in the air compared with the maximum amount the air can hold at that temperature.
Yes. At 100% relative humidity, the air is saturated and condensation, fog, dew, or clouds may form depending on conditions.
Warm air can hold more water vapor than cold air, so relative humidity can change even when the actual moisture amount stays similar.
No. Dew point is normally equal to or lower than the air temperature. If it is entered higher, the calculator will treat the air as fully saturated.