Free relative humidity calculator using the Magnus formula. Calculate humidity percentage from dry bulb temperature and dew point or wet bulb temperature.
You might also find these calculators useful
Relative humidity indicates how much moisture is in the air compared to the maximum it can hold at that temperature. Our calculator uses the Magnus formula to accurately compute relative humidity from either the dew point or wet bulb temperature.
Relative humidity (RH) is the ratio of the current amount of water vapor in the air to the maximum amount possible at that temperature, expressed as a percentage. At 100% RH, the air is saturated and fog or dew forms. RH affects comfort, health, and many industrial processes.
Relative Humidity Formula
RH = (e / es) × 100%, where e = actual vapor pressure, es = saturation vapor pressureMaintain optimal 30-50% humidity for health and comfort indoors.
Predict fog, dew, and precipitation likelihood from humidity levels.
Control humidity for manufacturing, storage, and agriculture.
Monitor and control indoor humidity for building comfort and health.
Weather stations calculate humidity for forecasting precipitation.
Greenhouses and storage facilities monitor humidity for optimal conditions.
Preserve artifacts and documents by maintaining proper humidity levels.
For most people, 30-50% relative humidity is ideal indoors. Below 30% can cause dry skin and respiratory issues. Above 60% feels sticky and promotes mold growth.
Warmer air can hold more water vapor. When temperature rises but moisture stays constant, relative humidity drops. This is why heated indoor air in winter often feels very dry.
Dew point is the temperature at which air becomes saturated (100% RH). Wet bulb is the lowest temperature achievable through evaporative cooling. Both can be used to calculate relative humidity.
In theory, air can become supersaturated above 100% briefly before condensation occurs. In practice, 100% is the maximum as excess moisture condenses into fog or dew.