Temperature Converter
Convert between Celsius, Fahrenheit and Kelvin instantly, with exact formulas and all three scales shown side by side for every value.
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How It Works
Three temperature scales are in everyday use. Celsius sets water's freezing point at 0 °C and its boiling point at 100 °C, and is the standard almost everywhere. Fahrenheit, used in the United States, puts the same two points at 32 °F and 212 °F. Kelvin starts at absolute zero — the coldest anything can be — and uses the same degree size as Celsius, so 0 °C is 273.15 K.
The conversions are exact, not approximate: °F = °C × 9/5 + 32, °C = (°F − 32) × 5/9, and K = °C + 273.15. One curiosity: −40 is the same on both scales, −40 °C = −40 °F, the only temperature where Celsius and Fahrenheit agree.
Worked examples: 0 °C = 32 °F = 273.15 K (water freezes). 100 °C = 212 °F = 373.15 K (water boils). 20 °C (a comfortable room) = 68 °F = 293.15 K. Body temperature 37 °C = 98.6 °F.
How to Use This Converter
Enter a temperature, pick the units, and the answer updates live — with all three scales shown in the table underneath.
- Enter the temperature — any value, including negatives and decimals.
- Pick the "From" and "To" units — Celsius, Fahrenheit or Kelvin in either box.
- Read the result — the headline shows your chosen conversion, and the table shows the value on all three scales at once.
The Reset button restores the example (0 °C to °F) so you can start over.
Tips and Practical Advice
Temperature conversion is mostly about knowing which scale your source uses — the maths itself is just one formula. A few landmarks make mental conversion much easier.
- Memorise the anchor points. 0 °C = 32 °F (freezing), 20 °C = 68 °F (room temperature), 37 °C = 98.6 °F (body temperature), 100 °C = 212 °F (boiling).
- Use the quick estimate. Double the Celsius value and add 30: 20 °C becomes roughly 70 °F (exact: 68 °F) — close enough for weather, not for cooking.
- Remember the degree sizes differ. One Celsius degree is 1.8 Fahrenheit degrees, so a 10 °C rise is an 18 °F rise — the gap matters when a recipe or a thermostat talks about changes.
- Kelvin has no "degrees". It is just "273.15 K", not "273.15 °K" — and Kelvin is the scale science uses, because it starts at absolute zero.
Frequently Asked Questions
What is 0 °C in Fahrenheit?
32 °F. The formula is °F = °C × 9/5 + 32, so 0 × 9/5 + 32 = 32.
What is 100 °C in Fahrenheit?
212 °F — the boiling point of water at sea level. In Kelvin it is 373.15 K.
What is absolute zero?
Absolute zero is −273.15 °C (−459.67 °F, 0 K), the lowest temperature possible. Nothing can be colder than 0 K.
Where do Celsius and Fahrenheit meet?
At −40: −40 °C is exactly −40 °F, the only temperature that is the same on both scales.
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