You enter the current air temperature and relative humidity. The tool converts to Celsius if needed, then applies the Magnus-Tetens approximation to compute the dew point. It also calculates absolute humidity in grams per cubic meter. The Magnus-Tetens formula is accurate to within about 0.4 °C over normal atmospheric ranges (−45 to 60 °C).
Relative humidity depends on temperature — 50% RH at 30 °C feels much muggier than 50% RH at 10 °C. Dew point is an absolute measure of moisture, so a dew point above 16 °C always feels sticky regardless of the air temperature.
No. By definition, dew point cannot exceed the current air temperature. When they are equal, relative humidity is 100% and fog or condensation is likely.
Cool surfaces (concrete walls, pipes) can be below the dew point of the room air, causing condensation. Check the dew point — if it is near or above the surface temperature, moisture will form even if mid-room RH seems moderate.
Mold typically grows when surfaces stay damp for extended periods. Keeping indoor dew point below about 13 °C (55 °F) helps prevent condensation on cool surfaces and reduces mold risk. Dehumidifiers lower the dew point directly.
It is a well-known empirical formula that estimates the saturation vapor pressure of water as a function of temperature. Using constants a = 17.67 and b = 243.5 °C, it is accurate across the range most people encounter in daily weather.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.