Unit Converter
Convert between metric and imperial units across seven categories.
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Temperature Converter
Celsius, Fahrenheit and Kelvin, with the offset handled properly.
Temperature Converter tool
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Celsius
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Fahrenheit
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Kelvin
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Rankine
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Réaumur
| Reference point | Celsius | Fahrenheit | Kelvin |
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A temperature and a temperature difference convert differently. 10 °C is 50 °F, but a rise of 10 °C is a rise of 18 °F, because a difference has no offset to apply. The checkbox switches between the two.
About the Temperature Converter
Temperature Converter handles all five scales and, unusually, distinguishes a temperature from a temperature difference. That distinction is the one thing most converters get wrong, and it matters: 10 °C is 50 °F, but a rise of 10 °C is a rise of 18 °F.
The reason is that Celsius and Fahrenheit have different zero points as well as different degree sizes. Converting a temperature applies both the scale and the offset; converting a difference applies only the scale, because the offsets cancel. Anyone who has converted a thermostat setting or a temperature tolerance has met this problem.
Kelvin is an absolute scale, starting at absolute zero, which is why it takes no degree sign: 300 K, not 300 °K. Values below absolute zero are refused rather than converted, since they do not exist. And -40 is the single temperature where Celsius and Fahrenheit agree, which is worth remembering as a check on any conversion.
The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.
Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.
How to use the Temperature Converter
- Choose fromThe fields below change to match what you pick, so only the figures that matter to your case are asked for.
- Enter temperatureDecimals are fine, and thousands separators are accepted and ignored.
- Read the celsius, fahrenheit and kelvinThe figures update as you type. The Calculate button is there if you would rather press something, but nothing waits for it.
- Copy or check the resultCopy the summary with the copy button, or open the table to check it row by row and read the formula with your own numbers in it.
Features
- Shows celsius, fahrenheit, kelvin, rankine and réaumur together, so you are not running it twice
- A results table you can read across
- Prints the formula with your own figures substituted in
- Updates as you type, with no button to press and no page reload
- Copy the result in one click
- Free, no sign-up, and it runs entirely in your browser
Who uses this tool
The temperature converter is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:
- Converting an oven temperature between Celsius and Fahrenheit
- Reading a weather forecast in the other scale
- Converting a temperature tolerance or a rise rather than a reading
- Getting Kelvin for a scientific calculation
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 1.8 and add 32. To go back, subtract 32 and divide by 1.8. The mental shortcut is to double and add 30, which is close enough for weather.
Why is a 10 degree rise not 50 degrees Fahrenheit?
Because a difference has no zero point, so the +32 offset does not apply. A 10 °C rise is an 18 °F rise. Tick the difference box for this case.
Why does Kelvin have no degree symbol?
Because it is an absolute scale rather than a relative one. The correct form is 300 K.
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Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.