Temperature converter
Free temperature converter between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur. Handles the offset math correctly — unlike simple unit ratios, temperature scales need affine conversion.
Thermodynamic scales. Absolute and relative.
20 °C = 68 °F
How to use temperature converter
- 01Pick a category
Length, weight, temperature, or pressure. Each has its own dedicated page with the complete unit list.
- 02Type your value
Enter the number you want to convert. The result updates instantly as you type — no submit button.
- 03Swap units
Use the From and To pickers to choose any pair — metric, imperial, SI, or exotic. Swap with one click.
- 04Copy the result
Tap the copy button next to the output to paste the result anywhere.
- 05Reuse from history
Recent conversions are saved to your browser locally so you can re-run them without retyping.
Examples
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32: °F = °C × 9/5 + 32. Equivalently, °F = °C × 1.8 + 32. The converter does this automatically, including Kelvin and Rankine.
What's absolute zero?
The lowest possible temperature — 0 kelvin, which is −273.15 °C or −459.67 °F. Nothing can be colder; it's where all classical thermal motion stops.
Why does the Kelvin scale exist?
Kelvin is an absolute scale anchored at 0 K = absolute zero, which makes it the natural scale for thermodynamic equations. Its degree size matches Celsius, so you can add 273.15 to go from °C to K.
What's Rankine used for?
Rankine is the absolute-zero version of Fahrenheit, used in US engineering thermodynamics. 0 °R = absolute zero; each degree is the size of a Fahrenheit degree.
Last updated . Built by Tooligan.