Dew Point Calculator

Dew point from temperature and relative humidity using the Magnus formula.

Calculator Numbers & Math Updated Apr 20, 2026
How to Use
  1. Enter air temperature and relative humidity.
  2. Dew point and comfort band update live.
Input
Presets
Result

Show Work

Enter values to see the step-by-step calculation.

Formula

Magnus
α = (a·T)/(b+T) + ln(RH/100) · dp = (b·α)/(a−α) · a=17.625, b=243.04
Comfort
<10°C dry · 10-16 comfortable · 16-18 slightly humid · 18-21 humid · >21 very humid

About the Dew Point Calculator

Use the Dew Point Calculator — a free, easy tool for everyday maths and number work. Nothing is uploaded, and you do not need an account. Dew point from temperature and relative humidity using the Magnus formula.

How it works

Put each value in its box and read the answer as you go. Because it recalculates live, you can play with the inputs to see how each one moves the result — handy for checking your own working or planning ahead. Everything happens on your device, so it is fast and private.

Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.

Frequently Asked Questions

How do I use the Dew Point Calculator?

Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.

Do I need to install or sign up for anything?

Not at all — it runs in the browser with nothing to install and no account. After it loads once, it even works without an internet connection.

Is my information private?

Yes. Everything happens in your browser. Nothing you type is sent to a server or saved anywhere.

Common Use Cases

Nothing to set up

Open the page and start. There is nothing to install, and no account to make.

Check your work

Worked it out yourself? Use the Dew Point Calculator to make sure your answer is right.

Learn while you do it

Seeing what you put in and what comes out helps you understand how they fit together.

No data leaves your browser

The tool runs locally, so whatever you enter stays with you and only you.

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