How to Use the Humidity Converter
The relative humidity (%) you see in a weather forecast can mean very different actual moisture levels depending on temperature. This converter takes your temperature and relative humidity and instantly calculates absolute humidity — the actual mass of water vapor in grams per cubic meter of air.
The calculation uses the Magnus-Tetens approximation, a formula widely used in meteorology. It first finds the saturation vapor pressure at the given temperature, multiplies it by the relative humidity ratio to get actual vapor pressure, then converts that into absolute humidity in g/m³.
Absolute humidity is especially useful for sizing dehumidifiers and humidifiers. A summer room at 86°F and 70% RH has very high absolute humidity, meaning a dehumidifier has to pull out a lot of moisture, while a heated winter room at 68°F and 20% RH has low absolute humidity, meaning a humidifier needs to add a lot. Looking at relative humidity alone can hide how much the real seasonal load actually differs.
Frequently Asked Questions
Relative humidity is a percentage of the maximum moisture the air could hold at that temperature, so it shifts with temperature. Absolute humidity is the actual mass of water vapor per cubic meter of air, so it shows real moisture content directly.
Yes — the bigger the gap between your current and target absolute humidity, the more moisture needs to be removed or added, meaning you'll need a higher-capacity unit.