Psychrometric & Humidity Calculators

A free suite of professional psychrometric calculators for HVAC engineers, building scientists, and curious homeowners. Every tool runs on the same peer-reviewed equations used in mechanical design — the Magnus dew-point formula, the Stull wet-bulb approximation, and the ideal-gas moist-air relations — so you can analyze dew point, wet bulb, enthalpy, air density, mixed-air states, and condensation risk directly in your browser. Pick a calculator below to size equipment, troubleshoot moisture problems, or simply understand how temperature and humidity shape the air around you.

Dew Point — Find the temperature at which water vapor condenses, using the Magnus-Tetens formula. Knowing the dew point tells you when surfaces will sweat, when mold can take hold, and how much latent moisture the air carries.
Wet Bulb — Calculate the thermodynamic wet-bulb temperature from dry-bulb temperature and relative humidity with the Stull (2011) approximation — the lowest temperature reachable by evaporative cooling, used for cooling-tower sizing and heat-stress (WBGT) screening.
Mixed Air — Blend two air streams — such as return air and outdoor air in an economizer mixing box — by mass fraction to find the resulting temperature, humidity ratio, and enthalpy of the combined airstream.
Sensible & Latent Heat — Break a cooling or heating load into its sensible and latent parts from airflow and state differences, then report the total load and the Sensible Heat Ratio (SHR) that governs equipment selection in humid climates.
Enthalpy — Compute the total heat content of moist air in kJ/kg of dry air, combining sensible heat (temperature) and latent heat (moisture). Enthalpy differences drive the coil loads HVAC engineers use for energy modeling.
Air Density — Determine the density of moist air from temperature, humidity, and barometric pressure via the ideal-gas law. Essential for fan and duct selection, airflow corrections, and aerodynamic estimates at altitude.
Condensation Risk — Assess interstitial condensation in multi-layer walls using one-dimensional steady-state heat transfer, comparing layer temperatures against the dew point to flag where moisture is likely to accumulate.