Psychrometric Calculator (Moist Air)
What are the wet-bulb, dew point, humidity ratio and enthalpy of this air?
Single calculationv1.0.0Verified 2026-11-01Runs in your browser
Spec sheet
ashrae_2017_psychrolib · v1.0.0Method
ASHRAE Handbook — Fundamentals (2017) ch. 1, via PsychroLib
- 01
p_ws: Hyland–Wexler (ASHRAE eqn 5, 6) - 02
W = 0.621945 · p_w / (p − p_w) - 03
h = 1.006·t + W·(2501 + 1.86·t) kJ/kg - 04
Wet bulb: bisection on ASHRAE eqn 33/35 - 05
p(z) = 101325·(1 − 2.25577e−5·z)^5.2559
Limits — read before relying on it
- Valid for −100 °C to 200 °C (ASHRAE fit range).
- Ideal-gas mixture; ASHRAE notes the saturation-pressure fit is within 300 ppm of tabulated values.
- Standard-atmosphere pressure for the altitude; enter weather-station pressure for exact work.
Sources
- PsychroLib (MIT) — ported to TypeScript ↗library
- ASHRAE Handbook — Fundamentals (2017), chapter 1standard