Free online tool to calculate precise dew point temperatures instantly using the Magnus formula. Check condensation risk and prevent mold in seconds. No sign-up required.
Dew point is like a cold glass of water on a summer day. If the glass gets colder than the dew point, water droplets form on it. It’s the threshold where condensation begins!
Uses Magnus formula (a=17.27, b=237.3°C). Accurate for -40°C to +60°C.
Rule of Thumb: If a surface is colder than the calculated dew point, it will sweat. Keep surfaces warmer or air drier.
Checklist: Enter Dry-Bulb Temp. Enter Relative Humidity. Verify the Dew Point is comfortably below your coldest indoor surface.
Quick Tip: HVAC systems usually target an indoor dew point below 12°C (55°F) for maximum comfort and mold prevention.
Condensation forms when the glass temperature drops below the dew point of the indoor air. This happens most often in winter when the air is humid and the glass is cold.
To prevent mold, you must keep indoor surfaces above the dew point or lower the indoor dew point by using a dehumidifier to remove moisture from the air.
Yes. When the air temperature equals the dew point, the relative humidity is 100%, and the air is fully saturated with water vapor.