Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin, and Rankine at once.
| Reference | °C | °F | K | °R |
|---|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0.00 | 0.00 |
| Freezing point of water | 0.00 | 32.00 | 273.15 | 491.67 |
| Room temperature | 20.00 | 68.00 | 293.15 | 527.67 |
| Body temperature | 37.00 | 98.60 | 310.15 | 558.27 |
| Boiling point of water | 100.00 | 212.00 | 373.15 | 671.67 |
How to convert temperature units
Enter a temperature
Type the value you want to convert, including a minus sign if it is below zero.
Pick the scale it is in
Choose Celsius, Fahrenheit, Kelvin, or Rankine as the scale your number is measured on.
Read all four results
The four result cards update instantly with the same temperature on every scale.
Copy the results
Use the copy button to put all four values on your clipboard, one per line.
Why use this tool
Four scales at once
Celsius, Fahrenheit, Kelvin, and Rankine all update from a single value, so you never chain two conversions together.
Offset math, done correctly
Temperature scales have different zero points, so each conversion runs through an explicit formula rather than a single multiplier.
Absolute zero warning
Enter anything below minus 273.15 Celsius and the tool flags it as physically impossible instead of quietly returning a negative Kelvin.
Adjustable precision
Round to whole degrees for a weather forecast, or show up to four decimal places for lab and engineering work.
Runs on your device
Every calculation happens in the page as you type. Nothing is uploaded and no account is required.
About this tool
The Temperature Converter takes one value and shows it on all four common scales at the same time. Type a number, pick whether it is Celsius, Fahrenheit, Kelvin, or Rankine, and the four result cards update as you type. There is no convert button, and no need to run a second conversion to get from Fahrenheit to Kelvin.
Temperature is not like length or weight. Those are ratio scales, where doubling the number doubles the quantity and a single multiplier converts between any two units. Temperature scales have different zero points, so 20 Celsius is not twice as hot as 10 Celsius, and multiplying by a factor gives the wrong answer. This tool converts every input to Kelvin first using the formula for that scale, then converts out of Kelvin into each of the other three. Celsius adds 273.15, Fahrenheit adds 459.67 then scales by five ninths, and Rankine is a straight five ninths.
Absolute zero is the coldest possible temperature: minus 273.15 Celsius, minus 459.67 Fahrenheit, and zero on both Kelvin and Rankine. Nothing is clamped here, so if you enter a colder value the math still runs and you still see the numbers, but a warning appears telling you the input is below the physical floor. That is usually a sign of a typo or a missing minus sign rather than a real reading.
For a focused two-field version, use Celsius to Fahrenheit. For other measurements, see the length converter and the energy converter.
Frequently asked questions
- How do I convert Celsius to Fahrenheit?
- Multiply the Celsius value by 1.8 and add 32. So 20 Celsius is 68 Fahrenheit. Going the other way, subtract 32 first and then divide by 1.8.
- What is Rankine and who uses it?
- Rankine is an absolute scale that starts at absolute zero but uses degrees the same size as Fahrenheit degrees. It shows up in thermodynamics and some US engineering work, where an absolute scale is needed but the numbers should stay in familiar Fahrenheit-sized steps.
- Why can I not just multiply by a conversion factor?
- Because temperature scales start at different zero points. A factor alone works for length or weight, where zero means the same thing on every scale. For temperature you also need the offset, which is why this tool routes every conversion through Kelvin.
- What happens if I enter a value below absolute zero?
- The results still appear, since nothing is clamped, but a warning tells you the value is colder than absolute zero and therefore physically impossible. Absolute zero is minus 273.15 Celsius, minus 459.67 Fahrenheit, and zero Kelvin.
- Are my numbers sent anywhere?
- No. All conversion happens on your device inside the page. Nothing you type is uploaded or stored.
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