Dew Point Calculator

Computes water vapor partial pressure from dry-bulb temperature and RH, then inverts the same vapor-pressure curve to obtain dew point. Intended for quick HVAC and classroom checks, not meteorological certification.

Free · No limits · Runs in your browser

How to use

  1. 1Enter dry-bulb temperature in °C.
  2. 2Enter relative humidity strictly between 0 and 100%.
  3. 3Read saturation pressure, vapor pressure, and dew point.

Frequently asked questions

Why must RH be above zero?
At RH = 0 the vapor pressure is zero and dew point is undefined for this model.
Is this valid below freezing?
The curve is treated as liquid water; frost point and ice effects are not modeled.

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