Fahrenheit to Celsius

The United States remains one of the holdout countries that still uses Fahrenheit on a daily basis. Even the U.S. relies on Celsius (or Kelvin) temperature scales for scientific research. For any student entering basic chemistry or physics, the importance of being able to convert from Fahrenheit to Celsius is supremely important. Likewise, it is also invaluable in knowing how to convert Celsius to Fahrenheit. The mathematics are pretty basic, it is just a matter of remembering a simple formula. With just a bit of practice it will become second nature and you can do it very rapidly.

The Fahrenheit to Celsius conversion formula:

The formula to convert degrees Fahrenheit to Celsius (occasionally still called centigrade) is as follows:

Celsius = (Fahrenheit – 32) x 5/9

An example is converting 212 Fahrenheit to Celsius. This is, of course, the boiling point of water.

Using the above formula we get:

Celsius = (212 – 32) x 5/9


Celsius = (180) x 5/9


Celsius = 100

and this is true because we all know the boiling point of water is 100 degrees Celsius.

The Celsius to Fahrenheit conversion formula:

Converting from Celsius to Fahrenheit is just as easy and probably more useful since the majority of the world is using celsius and converting celsius to fahrenheit helps us understand temperatures more clearly here in the United States. A bit of algebra applied to the original formula allows us to solve for Fahrenheit and achieve:

Fahrenheit = [(Celsius) x 9/5] + 32

So, let us convert 0 degrees Celsius (the freezing point of water) to Fahrenheit.

From above we get:

Fahrenheit = [( 0 x 9/50)] + 32


Fahrenheit = (0) + 32


Fahrenheit = 32

and again, this makes sense since this is the freezing point of water in Fahrenheit.

The 9/5ths and 5/9ths can cause confusion. This fraction is based on the amount of units of each temperature scale between the two points of boiling and freezing. For instance, on the Celsius scale there are 100 degrees from freezing to boiling (0 to 100) and on the Fahrenheit scale there are 180 degrees from freezing to boiling (32 to 212). These two ranges compared to one another are 100/180 or 5/9ths.

An interesting fun fact is that the scales converge at –40 degrees (burrrr). If you want, try converting –40 from one scale to the other. You will see that it is still –40 degrees. So whenever it is minus 40 outside, you don't have to care at all whether the weatherman says Fahrenheit or Celsius!

The metric system is the universal language of science and to stay competitive and in tune with the rest of the world, it is important to be able to do these basic conversions. Like any mathematics, practice makes perfect. Don't be afraid to use a fraction calculator to key in the fractional parts of the formula, too.