How dew point temperature is calculated
The dew point is the temperature to which air must be cooled at constant barometric pressure for water vapour to condense into liquid dew.
Using the Magnus-Tetens psychrometric approximation, dew point provides a much more reliable gauge of human comfort and stickiness than relative humidity alone.
Worked example
At an ambient air temperature of 22.0°C (71.6°F) and relative humidity of 55%:
The dew point temperature is 12.5°C (54.5°F), producing a dew point depression of 9.5°C. This is classified as comfortable and pleasant for indoor and outdoor activities.
Inputs for the dew point calculator
Temperature scale
Choose between Celsius (°C) and Fahrenheit (°F).
Air temperature
The dry-bulb ambient air temperature.
Relative humidity
The current relative humidity percentage from 1% to 100%.
CALCULATOR QUESTIONS
Dew point calculator questions
Why is dew point better than humidity for measuring comfort?
Relative humidity changes as temperature rises and falls throughout the day, whereas dew point directly measures absolute moisture content in the air.
What dew point feels humid and oppressive?
Dew points above 18°C (65°F) feel sticky and humid, while dew points exceeding 21°C (70°F) feel oppressive and interfere with sweat evaporation.