Celsius to Fahrenheit
Multiply by 9/5 and add 32. The offset is why this is not a single factor like every other conversion on the site, and the page shows both parts.
The offset is what makes this different from every other conversion on the site: multiply by 9/5 first, then add 32. There is no single factor, which is why −40 is the one temperature that reads the same on both scales.
With temperature 72, temperature converter comes to 161.60 — converted value. It is reached in 4 steps, the last of which is 72 * 0 + 161.6 * 1 + 345.15 * 0, and each one is printed on the page with its numbers filled in. The formula is the one published by NIST, not an approximation fitted to it.
Formula and sources checked · How we check
- In Celsius
72 * 1 + (72 - 32) * 5 / 9 * 0 + (72 - 273.15) * 072 °C- In Fahrenheit
72 * 9 / 5 + 32161.6 °F- In Kelvin
72 + 273.15345.15 K- Converted value
72 * 0 + 161.6 * 1 + 345.15 * 0161.6
Is there a way to do it in your head?
Double it and add 30. That is right to within a couple of degrees across ordinary weather: 20°C gives 70 against a true 68. The error grows with the number, so it serves for a forecast and not for an oven, where 200°C would come out 430 instead of 392.
Which fixed points are worth memorising?
Water freezes at 0 and 32, a room is 20 and 68, body temperature is 37 and 98.6, water boils at 100 and 212, and the two scales cross at −40. Those five anchor almost every temperature you will meet, and the arithmetic only has to fill the gaps between them.
The formula
- In Celsius
value * from_c + (value - 32) * 5 / 9 * from_f + (value - 273.15) * from_k - In Fahrenheit
celsius * 9 / 5 + 32 - In Kelvin
celsius + 273.15 - Converted value
celsius * to_c + fahrenheit * to_f + kelvin * to_k
Formula from NIST — SI units and temperature scales, BIPM — the kelvin and the International System of Units.
The same calculator, other cases
Undecided? The Temperature Converter carries every case behind one control.