Dew Point Calculator
At what temperature will the air start to condense?
Single calculationv1.0.0Verified 2026-11-01Runs in your browser
Spec sheet
magnus_alduchov_eskridge · v1.0.0Method
Magnus formula (Alduchov & Eskridge 1996 coefficients)
- 01
γ = ln(RH/100) + a·T/(b + T) - 02
Td = b·γ / (a − γ) - 03
a = 17.625, b = 243.04 °C
Limits — read before relying on it
- Over liquid water; below 0 °C the frost point is slightly higher.
- Coefficients fitted for −40 °C to 50 °C (saturation vapor pressure error below 0.4 %); outside that range the result is an extrapolation.
Sources
- Alduchov & Eskridge (1996), Improved Magnus form approximation of saturation vapor pressure, J. Appl. Meteor. 35, 601–609standard