The graphic above shows how temperatures on the Fahrenheit scale relates to the Celsius scale. If you want a more exact conversion, use the following formula:

Tc = (5/9)*(Tf-32)

For example, suppose you have a Fahrenheit temperature of 98.6 degrees and you wanted to convert it into degrees Celsius. Using the above formula, you would first subtract 32 from the Fahrenheit temperature and get 66.6. Then you multiply 66.6 by five-ninths and get 37 degrees Celsius. 

The formula to convert a Celsius temperature into degrees Fahrenheit is: 

Tf = (9/5)*Tc+32

For example, suppose you have a Celsius temperature of 100 degrees and you want to convert it into degrees Fahrenheit. Using the above formula, you first multiply the Celsius temperature reading by nine-fifths and get 180. Then you add 32 to 180 and get 212 degrees Fahrenheit. 

Another method that works just as well and might be easier to remember is the following: Regardless of which direction you want to covert, Fahrenheit to Celsius or Celsius to Fahrenheit, always first add 40 to the number. Next, multiply by 5/9 or 9/5 just like the old method. Then, always subtract out the 40 you just added. 

This works because, as you can see in the graphic above,

-40°Fahrenheit = -40°Celsius

To remember whether to use 5/9 or 9/5 when converting from Fahrenheit to Celsius or Celsius to Fahrenheit, just simply remember, F (for Fahrenheit) also can stand for Fraction. 5/9 is always a Fraction; 9/5, while also a fraction in this form, is Clearly a whole number plus a fraction (1 and 4/5). So, if you want to convert Fahrenheit (F) to Celsius (C), then use the Fraction 5/9; Celsius (C) to Fahrenheit (F), use the other, 9/5, which is Clearly not just a fraction. 

For an example, we'll use the values above: 98.6°F and 37°C, which are equal. 

To convert from F° to C°: