Estimate dew-point temperature from air temperature and relative humidity with the Magnus formula.
| Dew point (°C) | – |
Use this calculator when you want the temperature at which moist air, cooled at constant humidity, reaches saturation. The August–Roche–Magnus fit uses a = 17.625 and b = 243.04 °C. Relative humidity is entered from just above 0 up to 100%.
20 °C and 60% RH give a dew point near 12 °C. This is an empirical weather fit, not a laboratory vapour-pressure table, and it is meant for ordinary meteorological temperatures, not industrial dryers or cryogenic gases.
Air T (°C): Dry-bulb air temperature in Celsius.
RH (%): Relative humidity, greater than 0 and at most 100.
Dew point (°C): Td from the Magnus inversion, in Celsius.
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