Online Dew Point & Humidity Calculator
Determine air dew point temperature and condensation risks on building envelope surfaces and window panes based on indoor air temperature and relative humidity.
Humidity & Dew Point Calculator
Calculate dew point using Magnus formula, absolute humidity (g/m³), vapor pressure, and condensation/mold risks
Dew point is the temperature at which air becomes 100% saturated with water vapor and begins condensing into liquid droplets.
Calculation Results
How to use
- Enter ambient air dry-bulb temperature (°C or °F).
- Input relative humidity percentage (%).
- View computed dew point temperature and condensation evaluation.
- Compare dew point with glass/wall surface temperature to forecast condensation risk.
Calculation Example
At ambient air temperature 20 °C and 60% relative humidity, the dew point is approximately 12 °C. Any surface below 12 °C will trigger water vapor condensation.
Calculation Methodology
Dew point calculations employ the Magnus-Tetens approximation relating saturation vapor pressure to temperature and relative humidity.
Frequently Asked Questions
What is the dew point?
The temperature at which air becomes 100% saturated with water vapor and moisture begins to condense.
What is considered healthy indoor humidity?
Indoor relative humidity between 40% and 60% is generally regarded as healthy and comfortable.
Why does condensation form on windows?
When window glass surface temperature drops below indoor air dew point, moisture condenses onto the pane.
Can dew point be reduced?
Yes, lowering humidity through mechanical ventilation or dehumidifiers reduces the dew point.
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