Dew Point Calculator
Estimate the dew point temperature from ambient air temperature and relative humidity using the Magnus formula.
For meteorological estimation only; instruments provide the most accurate readings.
Examples
- 30 °C with 70% humidity ⇒ 23.9 °C (75.0 °F) dew point
- 18 °C with 40% humidity ⇒ 4.2 °C (39.5 °F) dew point
FAQ
Can I input Fahrenheit?
Convert to Celsius first, or compute manually and compare with the Fahrenheit result shown in parentheses.
What happens at 100% humidity?
At saturation, the dew point equals the air temperature; the calculator caps humidity at 100%.
Why is humidity below 1% not allowed?
Extremely low humidity can cause numerical issues; the formula clamps the minimum to a small positive value.
Additional Information
- Dew point is the temperature at which water vapor condenses; higher values indicate muggy air.
- The Magnus approximation (a = 17.27, b = 237.7 °C) is accurate for everyday HVAC and weather use.