Temperature Converter
Convert temperature instantly between Celsius, Fahrenheit and Kelvin with this free, easy-to-use converter right in your browser.
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Minimum 0
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter a temperature in any one box — Celsius, Fahrenheit or Kelvin.
- Press Calculate to see the other two, plus the UK oven gas mark in the baking range.
How it works
Whatever you type is converted to a common scale, then back out: °F = °C × 9/5 + 32, K = °C + 273.15, and the reverse °C = (°F − 32) × 5/9.
Because the scales have different zero points, this is an offset (affine) conversion, not a simple multiply — so it works in every direction.
Worked example
180 °C (a common oven temperature). = 356 °F, 453.15 K, and roughly UK gas mark 4. Enter 356 °F instead and you get 180 °C back.
Common mistakes
- Mixing up the C↔F formula — it's × 9/5 then + 32, not the other way.
- Forgetting Kelvin has no degree sign and starts at absolute zero.
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32 — so 20°C = 20 × 1.8 + 32 = 68°F.
What is 0 Kelvin?
Absolute zero — the coldest possible temperature, equal to −273.15°C.
Can I convert Fahrenheit to Celsius too?
Yes — enter the value in the Fahrenheit (or Kelvin) box and the other scales are filled in. Enter only one box at a time.
What are oven gas marks?
A UK oven scale: gas mark 1 ≈ 140 °C up to gas mark 9 ≈ 240 °C. The tool shows the nearest mark when your temperature is in the baking range.
What is absolute zero?
0 K, which is −273.15 °C — the coldest possible temperature. The tool won't accept anything colder.
Related tools
Explore more in Units, Measurement & Converters.
Cite this tool
Zerdly. (2026). Temperature Converter. Retrieved from https://www.zerdly.com/tools/temperature-converter/
Tip: Enter any known values to calculate the remaining results.
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