Mixing Ratio of Air Calculator
Compute water vapor mixing ratio (g/kg)
How to Use This Calculator
1
Enter Temperature
Provide air temperature in °C.
2
Enter Pressure
Provide station pressure in hPa.
3
Enter Relative Humidity
Provide RH as a percentage (0–100%).
4
Calculate
View mixing ratio in g/kg and kg/kg.
Formula
e_s(T) = 6.112 · exp((17.67·T)/(T+243.5)) [hPa]
e = RH/100 · e_s(T)
w = 0.622 · e / (p − e)
Where: T in °C, p in hPa, RH in %; w in kg/kg (×1000 → g/kg)
About Mixing Ratio
Mixing ratio expresses the mass of water vapor per unit mass of dry air. It is widely used in meteorology and HVAC psychrometrics.
Frequently Asked Questions
How is mixing ratio different from specific humidity?
They are similar at typical atmospheric conditions; specific humidity uses total moist air mass as denominator.
Why use g/kg?
g/kg is more intuitive for HVAC and weather discussions than kg/kg.