Convert Temperature
Convert between Celsius, Fahrenheit and Kelvin. Handles the offset properly, which a simple multiplication cannot.
Runs entirely in your browser — nothing is uploaded
1 °C equals
33.8°F
1 °C in every unit
- Celsius
- 1 °C
- Fahrenheit
- 33.8 °F
- Kelvin
- 274.15 K
Minus forty is the same number in both
−40 °C is exactly −40 °F. It is the one point where the two scales cross, and it is a useful sanity check on any converter — including this one.
It happens because the scales differ in two ways at once: they start in different places and they run at different rates. Somewhere below zero, the two disagreements cancel out.
This is why a factor table would be wrong
Most unit conversions are a single multiplication. Temperature is not, because the scales do not share a zero: Fahrenheit needs both a scale and a shift, so 20 °C is 68 °F rather than any multiple of twenty.
That is the reason each unit on this site declares how to reach a base unit and how to come back, instead of carrying one number. It costs nothing for the straightforward families and it makes this one correct rather than special-cased.
Kelvin has no degrees
It is written 300 K, not 300 °K. The degree symbol was dropped in 1967, because a kelvin is an absolute amount rather than a position on a scale that somebody chose.
Zero kelvin is absolute zero, the point where there is no thermal energy left to remove. There is nothing below it, which is why a negative kelvin figure means an input error rather than a very cold day.
Nothing is sent anywhere
Every conversion on this page is arithmetic done in your own browser. No request is made, nothing is stored between visits, and the page keeps working with the connection switched off — which is a reasonable way to check the claim.
Frequently asked questions
What is the quick mental conversion?
Double the Celsius and add thirty. 20 °C gives 70, against a true 68 — close enough for deciding what to wear, and wrong enough that you should not use it for cooking or anything medical.
What is normal body temperature?
37 °C, which is 98.6 °F. That famous figure is a conversion artefact: the original nineteenth-century measurement was 37 °C to the nearest degree, and converting it produced a false air of precision that has stuck for over a century.
Why does the United States still use Fahrenheit?
Largely inertia. Fahrenheit arrived first and became embedded in weather reporting, cooking and medicine, and there has never been enough pressure to make the switch worth its cost. American science and medicine use Celsius; American weather forecasts do not.
Is anything sent anywhere?
No. The conversion is done in this tab, nothing is transmitted, and the page works offline.