How to use Celsius to Fahrenheit Converter — °C to °F
- 1Pick the kind of measurement, then the unit you are converting from and to.
- 2Type your value — the result updates as you type.
- 3Scroll down for the same value in every other unit, and a table of common conversions.
About Celsius to Fahrenheit
Celsius and Fahrenheit are the awkward pair because they disagree about two things at once: how big a degree is, and where zero sits. Fahrenheit degrees are 5/9 the size of Celsius degrees, and its zero is 32 degrees below freezing. Both facts have to be applied, in the right order, which is why mental conversion goes wrong so much more often than it does for metres and feet.
The rough rule — double it and add 30 — is fine for weather and misleading everywhere else. At 20 °C it gives 70 against a true 68; at 200 °C it gives 430 against a true 392, an error of nearly 40 degrees. For an oven, a sous-vide bath or a datasheet tolerance, the real formula matters, and this converter applies it exactly.
Kelvin and Rankine are included because they turn up whenever the physics gets serious. Kelvin measures from absolute zero, which makes it the scale where ratios actually mean something — twice the kelvins really is twice the thermal energy, while "twice as many degrees Celsius" means nothing at all. Rankine does the same job with Fahrenheit-sized degrees and still appears in older US engineering tables.