Why can't I convert temperature by multiplying alone?

Because Celsius and Fahrenheit have different zero points as well as different degree sizes. The conversion is a scale and an offset, F = C x 9/5 + 32, so 0 degrees in one is not 0 in the other. Kelvin shares the Celsius degree size and only shifts the zero.

At what temperature do Celsius and Fahrenheit agree?

At minus 40. It is the one point where the scale and the offset cancel, which makes it the standard sanity check for anything doing this conversion.

Conversionsmeasurement

Temperature Converter

Temperature between Celsius, Fahrenheit and Kelvin. Unlike every other converter on the site this one has an offset as well as a scale, which is why you cannot convert a temperature *difference* the same way.

Also called: celsius to fahrenheit, c to f, kelvin converter.

Result

98.6

37° c is 98.6° f.

In Celsius

In Fahrenheit

98.6

In Kelvin

310.15

A change of this many degrees C, in F

66.6

Degrees above absolute zero

310.15

Against familiar reference points

Between body temperature and the boiling point of water.

Note

To convert a temperature *difference* rather than a temperature, use the scale factor only: 1 °C of change is 1.8 °F of change.

How this is calculated

Method and background

How this is calculated

Celsius and Fahrenheit share no zero point, so the conversion is affine rather than a simple multiplication. That matters more than it sounds: a rise of 10 °C is a rise of 18 °F, not 50 °F, and applying the full formula to a difference is a common and quiet error. Kelvin shares Celsius's scale with an offset to absolute zero.

F = C * 9/5 + 32; K = C + 273.15

C: Degrees Celsius

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

body temperature

Temperature: 37
From: Celsius
To: Fahrenheit

Result98.6

arithmetic identity: 37 x 9/5 + 32

Open this example

absolute zero

Temperature: 0
From: Kelvin
To: Celsius

Result-273.15

definition of the Kelvin scale

Open this example

the scales cross at -40

Temperature: -40
From: Celsius
To: Fahrenheit

Result-40

boundary: the one temperature where both scales agree

Open this example

Frequently asked questions

Why can't I convert temperature by multiplying alone?: Because Celsius and Fahrenheit have different zero points as well as different degree sizes. The conversion is a scale and an offset, F = C x 9/5 + 32, so 0 degrees in one is not 0 in the other. Kelvin shares the Celsius degree size and only shifts the zero.
At what temperature do Celsius and Fahrenheit agree?: At minus 40. It is the one point where the scale and the offset cancel, which makes it the standard sanity check for anything doing this conversion.