The formula C = 5/9 x (F-32) is used for converting Fahrenheit to Celsius. Plug in the temperature in degrees Fahrenheit for the term F in the equation. Subtract 32 from F and multiply the difference by 5/9. The result is the temperature in degrees Celsius.
The above equation can also be reversed into the equation F = (9/5C) + 32, and used for converting Celsius to Fahrenheit. Plug in the temperature in degrees Celsius for C, multiply by 9/5 and add 32 to the product. The result is the temperature in degrees Fahrenheit. In either case, it is important to follow the order of operations correctly. Multiplying F by 5/9 first and then subtracting 32 yields an incorrect answer. Always begin with the operation in parentheses.
The Fahrenheit scale, first developed by Daniel Gabriel Fahrenheit in the 18th century, sets the freezing point of water at 32 degrees and the boiling point of water at 212 degrees. It is still commonly used in the United States, though scientists and doctors are more likely to use the Celsius scale, which takes the freezing point of water to be zero degrees and the boiling point to be 100 degrees. It was named for Swiss astronomer Anders Celsius, who developed a similar scale in 1742.