Converting temperatures from Fahrenheit to Celsius requires two simple mathematical calculations. Using a calculator ensures accuracy and simplifies the overall process. Performing the two steps should only take a minute or so.
Subtract 32 from the Fahrenheit temperature
The first step in the temperature conversion process is to deduct 32 from the known Fahrenheit temperature. Using the example value in this question, 70 minus 32 equals 38.
Multiply the intermediate result by 5/9
The number obtained in the subtraction step is then multiplied by 5/9. Working with the example, 38 times 5/9 gives a result of approximately 21.1 degrees Celsius. As an alternative to multiplying by 5/9, one can divide by 9/5 or 1.8.
Check the result
Ensure that the result of your calculations makes sense. Consulting a table of reference temperatures with Celsius and Fahrenheit values is one way to gain confidence that you have performed the calculations correctly. Fahrenheit temperatures between 32 and 212 always convert to Celsius temperatures between 0 and 100.