Psychrometric Calculator
Find dew point, humidity ratio, and enthalpy from temperature and humidity.
Results
Dew point
13.858 °C
Wet-bulb temperature
17.998 °C
Humidity ratio
9.877 g/kg
Enthalpy
50.313 kJ/kg
Saturation vapor pressure
3.168 kPa
Usage examples
Estimating dehumidification load for an AC system
Find the humidity ratio from indoor dry-bulb temperature and relative humidity to estimate how much moisture needs to be removed to reach a target condition.
Checking the risk of condensation ahead of time
Find the dew point from indoor temperature and humidity to check whether a wall or window surface running colder than that could start condensing.
Estimating a cooling tower design value
Wet-bulb temperature is a key design reference for evaporative cooling systems — estimate it quickly from just dry-bulb temperature and relative humidity.
Frequently asked questions
What formulas does this use?
Saturation vapor pressure uses the Magnus-Tetens approximation, and wet-bulb temperature uses Stull's (2011) empirical formula. Both are widely validated as sufficiently accurate across the typical HVAC design range (0-50°C).
Can wet-bulb temperature really be calculated without iteration?
Yes. Classic wet-bulb calculations require iterative solving, but this tool uses Stull's non-iterative approximation, which computes it directly within about ±0.3°C of the true value.
Is this accurate at high altitude?
You can enter atmospheric pressure directly to account for altitude. The default, 101.325 kPa, is the sea-level standard.
Can I calculate from dew point instead of relative humidity?
This tool takes dry-bulb temperature and relative humidity as inputs; a dew-point-input mode isn't currently supported.