Dew Point Calculator

What is the Dew Point Calculator?

Calculate dew point from temperature and relative humidity (Magnus formula). Dew point is the temperature at which air becomes saturated, and it is a better guide to how muggy it feels than relative humidity alone.

How to use the Dew Point Calculator

1. Enter your temperature, your relative humidity.
2. Results update automatically as you type; you can also press Calculate.
3. Read the output: dew point, in fahrenheit.
4. Use the 📊 chart to see the result visually, then copy or share it.

Formula and method

Worked example

With temperature = 25 °C, relative humidity = 60 %, the Dew Point Calculator returns dew point: 16.69 °C; in fahrenheit: 62.05 °F.

Where the Dew Point Calculator helps in real life

You want to know whether a cold glass of water will sweat or whether fog might form tonight. Entering temperature and humidity gives the dew point to compare with the expected low.

You manage a basement and want to avoid condensation on cold pipes. If the pipe surface is below the dew point, moisture will collect there.

Common mistakes to avoid

• Treating relative humidity as an absolute measure of moisture.
• Entering Fahrenheit where Celsius is expected.
• Using indoor humidity for outdoor forecasts.
• Expecting exact results at very low humidity.

💡 Practical tip: When air temperature drops to the dew point overnight, expect dew, frost or fog by morning.

Tips for better results

• A dew point above about 20 °C (68 °F) usually feels sticky.
• Compare dew point with surface temperatures to predict condensation.
• Use a reliable hygrometer for indoor readings.

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