Temperature Converter
Celsius, Fahrenheit and Kelvin, live both ways — with the landmarks chart.
About this converter
Type in any of the three boxes — Celsius, Fahrenheit, Kelvin — and the others follow instantly, with a plain-language readout of what that temperature feels like. Below it, the landmark chart worth actually memorising, from −40° (the one temperature where both scales agree) to a moderate oven.
The formula, and the trick
Exact: °F = °C × 9/5 + 32 — Fahrenheit degrees are five-ninths the size of Celsius degrees and the scale starts 32 lower, which is why the conversion needs both a multiply and a shift. In your head: double it and add 30 lands within a couple of degrees anywhere between freezing and body heat (20 °C → 70 vs the true 68). Kelvin is Celsius with the zero moved to absolute zero, −273.15 °C — same degree size, no negative numbers, which is why science uses it. The three worth knowing cold: 0 °C = 32 °F (freezing), 37 °C = 98.6 °F (body), 100 °C = 212 °F (boiling).
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32: 20 °C × 1.8 + 32 = 68 °F. The quick mental version — double and add 30 — gets within a couple of degrees for everyday weather.
What temperature is the same in both scales?
−40°. It's the crossover point where °C and °F read identically — and a favourite exam question for exactly that reason.
What is normal body temperature in both scales?
37 °C = 98.6 °F, with normal variation of half a degree Celsius either way through the day. Fever conventionally starts at 38 °C / 100.4 °F.
Why does science use Kelvin?
Kelvin starts at absolute zero (−273.15 °C), so temperatures can't go negative and ratios mean something physically — 200 K really is twice as hot as 100 K in energy terms, which isn't true of 20 °C versus 10 °C.