Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin.
Common reference points
- Water freezes 0°C = 32°F = 273.15 K
- Water boils 100°C = 212°F = 373.15 K
- Average body temp 37°C = 98.6°F
- The crossing point −40°C = −40°F
- Absolute zero −273.15°C = 0 K
About this converter
Temperature trips people up in a way length and weight don't, because it isn't just a multiplication. Celsius and Fahrenheit start counting from different zero points, so converting between them takes a scale factor and an offset, not one number you multiply by. Kelvin avoids the problem entirely by starting at absolute zero, which is why physics uses it.
If you've ever wondered why a 20°C day doesn't feel "twice as hot" as a 10°C day even though 20 is double 10, that's the offset at work. In Fahrenheit those same temperatures are 68°F and 50°F, and 68 is nowhere near double 50 either. Neither scale has a true zero, so ratios between readings don't mean anything physically. Only Kelvin does, which is exactly why scientists bother with it.
Frequently asked questions
- Why isn't temperature just a simple multiplier like the other converters?
- Because Celsius and Fahrenheit don't share a zero point, 0°C is 32°F, not 0°F, converting requires both scaling and shifting the number. Length or weight units are always a fixed multiple of each other with no offset involved, which is why those conversions are simpler.
- What is 0 Kelvin, actually?
- Absolute zero, the coldest anything can theoretically get, the point where atomic motion stops. It works out to −273.15°C or −459.67°F. Nothing can go below it, so negative Kelvin readings don't exist.
- Is there a temperature where Celsius and Fahrenheit agree?
- Yes, −40. Both scales read −40 at exactly the same point, which is a fun one to just memorize.
- Why does the US use Fahrenheit when almost nowhere else does?
- Same story as feet and miles: Fahrenheit was already entrenched by the time metrication efforts happened, and daily weather and cooking never got a strong enough push to switch. Science and medicine in the US use Celsius and Kelvin anyway.