Absolute Humidity Calculator
Get g/m³ from temperature (°C) and relative humidity (%)
How to Use This Calculator
Enter Temperature
Type the air temperature in degrees Celsius.
Enter Relative Humidity
Provide RH between 0% and 100%.
Press Calculate
See absolute humidity in grams per cubic meter.
Formula
es(T) = 6.112 · exp((17.67 · T) / (T + 243.5)) [hPa]
e = RH/100 · es(T) [hPa]
AH = (2.1674 · e) / (T + 273.15) [g/m³]
Where: T = temperature in °C, RH = relative humidity in %
Example: T = 25°C, RH = 60% → es ≈ 31.67 hPa, e ≈ 19.00 hPa → AH ≈ 14.5 g/m³
About Absolute Humidity
Absolute humidity is the mass of water vapor per unit volume of air, expressed in grams per cubic meter (g/m³). It is useful for HVAC, weather analysis, and comfort assessment.
When to Use
- Indoor air quality: Compare moisture levels across rooms and seasons
- HVAC design: Determine dehumidification and ventilation requirements
- Storage: Protect humidity-sensitive goods and instruments
- Comfort: Understand muggy vs. dry conditions beyond RH alone
Tips
- Use accurate temperature and RH sensors for reliable results
- Temperature strongly affects saturation vapor pressure—measure at the same location
- Compare AH values to track moisture changes over time
Frequently Asked Questions
How is absolute humidity different from relative humidity?
Relative humidity is a percentage relative to saturation at a given temperature. Absolute humidity is an actual mass per volume (g/m³), independent of saturation.
What are typical indoor values?
Comfortable indoor absolute humidity commonly ranges from about 6 to 12 g/m³ depending on season and climate.
Does temperature change affect absolute humidity?
For the same moisture content, warming air lowers relative humidity but absolute humidity stays the same unless moisture is added or removed.