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Temperature Converter
Convert Celsius, Fahrenheit and Kelvin.
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- 1Enter detailsAdd the numbers for your scenario.
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- 3ReviewCheck totals, notes and breakdowns.
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How to use Temperature Converter
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Learn more about privacyTemperature is the one conversion you cannot do by multiplying, and that is why the mental shortcuts everyone uses for other units fail here. The scales have different zero points as well as different step sizes.
What Temperature Converter does
Converts between Celsius, Fahrenheit and Kelvin. Because the scales are offset, each conversion needs both a factor and an addition: °F = °C × 9/5 + 32, and K = °C + 273.15.
That offset is why doubling a temperature is meaningless. 20 °C is not twice as hot as 10 °C in any physical sense — only Kelvin, which starts at absolute zero, supports that kind of arithmetic.
Scales and reference points
| Celsius → Fahrenheit | × 9/5, then + 32 |
|---|---|
| Celsius → Kelvin | + 273.15 |
| Water freezes | 0 °C · 32 °F · 273.15 K |
| Water boils | 100 °C · 212 °F · 373.15 K |
| Absolute zero | −273.15 °C · −459.67 °F · 0 K |
| The scales cross at | −40 — the same number in °C and °F |
| Kelvin has no degree sign | Written "300 K", not "300 °K" |
| Why offsets matter | Ratios are only meaningful in Kelvin |
Detailed steps
- Enter the temperature.
- Choose the scale it is in.
- Read all three scales at once.
Worth knowing
−40 is the same in Celsius and Fahrenheit — the point where the two scales cross. It is a useful sanity check: if you have written a conversion and it does not agree at −40, the formula is wrong. It is also why the aviation industry can quote −40 without specifying which scale.
Frequently Asked Questions
Why can I not just multiply to convert temperature?
Because the scales have different zero points. Length units all start at zero length, so a single factor works. Celsius starts at water freezing and Fahrenheit 32 degrees below it, so the conversion needs an addition as well as a multiplication.
Is 20 °C twice as warm as 10 °C?
No. Ratios only mean anything on a scale that starts at absolute zero, which is Kelvin. In Kelvin those two are 293.15 and 283.15 — barely 3% apart, which is much closer to how they actually feel.
Why 273.15 and not 273?
Because the Kelvin scale is defined so that water’s triple point falls at exactly 273.16 K, putting 0 °C at 273.15 K. The .15 is not a rounding artefact; dropping it introduces a real error in scientific work.
Should I write °K?
No. Kelvin is an absolute unit and takes no degree symbol — 300 K, not 300 °K. Celsius and Fahrenheit do take it.
Is Temperature Converter free?
Yes. The Vootkit free plan includes 5 tool runs a day. Upgrade to Vootkit Pro for unlimited daily use, an ad-free workspace and saved workflows.
Are my files uploaded?
No. Temperature Converter runs entirely in your browser — your file is processed on your own device and never sent to a server. There is nothing for us to store or delete.
Do I need to install anything?
No. Temperature Converter works in any modern browser on desktop, tablet or phone. Open the page and start.
How often can I use it? Is there a daily limit?
On the free plan you get 5 tool runs a day. When you reach the limit you'll see a prompt to upgrade, and it resets the next day. Vootkit Pro removes the cap entirely for unlimited daily use.
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