Relative Humidity from Dew Point

The inverse of the dew point calculation.

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Formula

RH = 100 × e^(a·Td/(b+Td) − a·T/(b+T))

Example calculation

70 °F air, 50 °F dew point → 49% RH.

Practical HVAC use

Indoor humidity diagnostics.

Common mistakes

Entering wet-bulb as dew point.

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Dew Point

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Calculate dew point temperature from air temperature and relative humidity, in °F and °C.

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Check if a surface will condense moisture by comparing its temperature with the air's dew point.

Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators