Dew Point Calculator
Calculate dew point temperature, vapor pressure, absolute humidity, and condensation risk from temperature, relative humidity, and pressure.
Condensation on optical surfaces — lenses, windows, mirror substrates, or detector windows — occurs when the surface temperature drops below the dew point of the surrounding air. This tool computes dew point temperature from dry-bulb temperature (−40 to 60°C), relative humidity, and ambient pressure using the Magnus–Tetens formula (Sonntag 1990 / WMO coefficients). Additional outputs include saturation vapor pressure, actual vapor pressure, absolute humidity (g/m³), mixing ratio (g/kg), specific humidity (g/kg), and water vapor concentration in PPMv. A color-coded condensation risk indicator flags conditions where the dew point depression (T − T_d) falls below 5°C (elevated risk) or 2°C (imminent), useful for purging decisions, enclosure humidity management, and cryogenically cooled detector housings.