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Dew Point Calculator

Estimate dew point from air temperature, temperature unit, relative humidity with the Dew Point Calculator.

DEW POINT9.254294 °C

Magnus approximation at 50% RH; air temperature normalized to 20.00 °C.

Estimate based on the values shown
MethodMagnus dew-point approximation after normalizing temperature to °C.

Before you use the result

Check the entered units and assumptions before using the result for purchasing, construction, engineering, or safety decisions.

CALCULATOR GUIDE

How to use the Dew Point Calculator

Estimate dew point from air temperature, temperature unit, relative humidity with the Dew Point Calculator. Use it to check a practical estimate, paying close attention to the selected units and assumptions.

Step by step

  1. For the Dew Point, enter air temperature, temperature unit, relative humidity, result unit. Keep each value in the unit displayed beside its field.
  2. Review the selected Dew Point workflow and inputs, then read dew point in the result panel.
  3. Change one Dew Point assumption at a time to compare scenarios. Use Reset to restore this tool's worked example values.

How the calculation works

Magnus dew-point approximation after normalizing temperature to °C.

Worked example

In the Dew Point worked example, air temperature 20, temperature unit °C, relative humidity 50 %, result unit °C produces dew point of 9.254294 °C. Magnus approximation at 50% RH. Review the displayed units before comparing the result.

Understanding the result

The Dew Point reports dew point. Use it to check a practical estimate, paying close attention to the selected units and assumptions. Check the entered units and assumptions before using the result for purchasing, construction, engineering, or safety decisions.

How to check the answer

Check the Dew Point result by reversing the conversion or recomputing dew point from air temperature, temperature unit, relative humidity. For construction, electrical, weather, or purchasing decisions, compare the result with the applicable specification or professional guidance.

Common questions

What does the Dew Point calculate?

Estimate dew point from air temperature, temperature unit, relative humidity with the Dew Point Calculator.

Which Dew Point inputs have the biggest effect?

dew point responds directly to air temperature, temperature unit, relative humidity, result unit. Change one input while holding the others constant to see its effect.

Is the Dew Point result exact?

Check the entered units and assumptions before using the result for purchasing, construction, engineering, or safety decisions. Recheck air temperature, temperature unit, relative humidity and use dew point only for a decision where that level of precision is appropriate.

Formula tests, limits, sources, and guide registry updated September 1, 2026.
INTERPRET THE RESULTRead the other guideCheck assumptions, limitations and comparison methods →