Physics

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Dew Point Calculator.

Estimate dew-point temperature with the Magnus approximation.

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Results update as you type.

Dew point: 11.995454 °C

Dew point

11.995454°C

Results update automatically as you type.

Use Cases

Weather and Outdoor Planning

Check dew point to anticipate fog, dew, or comfort levels before outdoor activities.

Example: If air temp is 25°C and RH is 60%, dew point is about 16.7°C.

HVAC and Indoor Climate Control

Determine dew point to avoid condensation on surfaces and maintain comfortable indoor humidity.

Example: Set air conditioning to keep dew point below 15°C to prevent mold.

Frequently Asked Questions

What is dew point?
Dew point is the temperature at which air becomes saturated with moisture and water vapor condenses into liquid dew. It indicates the actual moisture content in the air.
How is dew point calculated?
This calculator uses the Magnus approximation, which estimates dew point from air temperature and relative humidity. It's a widely used formula that provides accurate results for typical atmospheric conditions.
Why is dew point important?
Dew point helps assess comfort levels, predict fog or dew formation, and is used in weather forecasting, HVAC design, and agriculture. Higher dew points feel more humid.

Tips & Common Mistakes

Tips

  • Enter air temperature in degrees Celsius and relative humidity as a percentage (0-100).
  • For accurate results, use a reliable hygrometer to measure relative humidity.
  • Dew point is always lower than or equal to air temperature; if equal, air is saturated.
  • Use dew point to assess comfort: below 10°C feels dry, above 20°C feels humid.

Common Mistakes to Avoid

  • Entering relative humidity as a decimal (e.g., 0.5) instead of a percentage (50).
  • Using Fahrenheit for air temperature; this calculator expects Celsius.
  • Confusing dew point with wet-bulb temperature or frost point.

Last updated: August 13, 2026