Celsius, Fahrenheit, Kelvin, All Three at Once
An American recipe says to preheat the oven to 425°F. Your oven dial is in Celsius. That’s 218°C, by the way, but good luck doing that conversion in your head while the kitchen timer’s going.
Type a temperature in any of the three scales and instantly see the other two. The conversion uses the exact formulas, not rounded approximations, so you get precise results for everything from baking to thermodynamics.
The Anchors Everyone Should Know
- Water freezes: 0°C = 32°F = 273.15 K
- Water boils: 100°C = 212°F = 373.15 K
- Body temperature: 37°C = 98.6°F = 310.15 K
- Room temperature: 20°C = 68°F = 293.15 K
- Absolute zero: -273.15°C = -459.67°F = 0 K
Most people can remember 0/32 and 100/212 and roughly interpolate between them. But for anything precise, especially in science where you need Kelvin, the formulas aren’t worth memorizing when a converter is this fast.
The Formulas (If You’re Curious)
- Fahrenheit = Celsius x 9/5 + 32
- Celsius = (Fahrenheit - 32) x 5/9
- Kelvin = Celsius + 273.15
Kelvin can’t go negative. It starts at absolute zero (0 K), which is the theoretical bottom of the temperature scale, the point where molecular motion essentially stops. That makes Kelvin the scale of choice for physics and chemistry, where negative temperatures don’t make physical sense.
Where This Comes Up
Travel. The weather app says it’s 35°C in Barcelona. Is that hot? (Yes. That’s 95°F. Bring water.) Or the ski report says -15°C in the Alps. How cold is that really? (5°F. Layer up.)
Cooking. British recipes use Celsius, American recipes use Fahrenheit, and they never seem to use the same round numbers. 180°C is 356°F, not 350°F. Close enough for most baking, but not for candy-making where five degrees matters.
Science and engineering. Gas law calculations need Kelvin. Thermodynamics problems need Kelvin. HVAC specs might arrive in either Celsius or Fahrenheit depending on the manufacturer’s home country.
For a broader set of unit conversions beyond temperature, length, weight, area, volume, speed, pressure, and energy, the Unit Converter covers all eight categories. Everything processes in your browser.