Humidity Ratio Calculator
Calculate the moisture content of air from temperature, relative humidity, and pressure
Calculator
Enter dry-bulb temperature, relative humidity, and atmospheric pressure to compute humidity ratio (moisture content of air).
About the Humidity Ratio Calculator
The Humidity Ratio Calculator allows you to determine the moisture content of air by using dry-bulb temperature, relative humidity, and atmospheric pressure. It calculates the humidity ratio (w), water vapor pressure, and saturation vapor pressure, making it essential for HVAC engineers, thermodynamics students, and professionals working with air-conditioning, drying systems, and atmospheric processes.
What You Can Calculate
- Humidity Ratio (w): The mass of water vapor per mass of dry air (kg/kg).
- Saturation Vapor Pressure (Psat): Maximum vapor pressure at a given temperature.
- Water Vapor Pressure (Pv): Actual vapor pressure based on relative humidity.
- Moist Air Properties: Useful for psychrometric and HVAC calculations.
Formulas Used in the Calculator
The calculator uses standard psychrometric relationships:
- Saturation Vapor Pressure: Psat = 0.61078 × exp(17.27T / (T + 237.3))
- Water Vapor Pressure: Pv = RH × Psat
- Humidity Ratio: w = 0.622 × (Pv / (P − Pv))
How to Use the Calculator
- Enter the dry-bulb temperature in °C.
- Enter the relative humidity (0–100%).
- Enter the atmospheric pressure in kPa.
- The calculator instantly displays humidity ratio and vapor pressures.
Applications of Humidity Ratio Calculation
Humidity ratio is a fundamental variable in psychrometrics, influencing heat transfer, mass transfer, and HVAC system design. It is critical for air-conditioning analysis, drying processes, building ventilation, climate studies, and environmental engineering. By understanding humidity ratio, engineers can evaluate air treatment loads and optimize comfort and energy efficiency.