Absolute Humidity Calculator
Enter the air temperature in Celsius and the relative humidity to find the absolute humidity, the actual mass of water vapor in each cubic meter of air. The result is in grams per cubic meter.
How to calculate absolute humidity
- Enter the air temperature in degrees Celsius.
- Enter the relative humidity as a percent from 1 to 100.
- Read the absolute humidity in grams per cubic meter.
Examples
Warm, humid room
T = 25 C, RH = 60%
Absolute humidity = 13.8 g/m3
Hot and very humid
T = 30 C, RH = 80%
Absolute humidity = 24.3 g/m3
Frequently asked questions
What is absolute humidity?
Absolute humidity is the actual mass of water vapor present in a given volume of air, regardless of temperature. It is usually measured in grams of water per cubic meter.
How is it different from relative humidity?
Relative humidity is the percent of the maximum vapor the air can hold at its temperature. Absolute humidity is the real amount of vapor present, so the same relative humidity holds more water in warmer air.
What formula does this calculator use?
It uses AH = (6.112 * exp((17.67*T)/(T+243.5)) * RH * 2.1674) / (273.15 + T), where T is in Celsius and RH is a percent, giving grams per cubic meter.
Why does warm air hold more water vapor?
Higher temperatures raise the saturation vapor pressure, so warmer air can hold more water before condensing. That is why a hot day at the same relative humidity feels muggier.
What is a typical absolute humidity indoors?
Comfortable indoor air is often around 7 to 12 g/m3. Very dry winter air can drop below 5 g/m3, while hot tropical air can exceed 25 g/m3.
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