Fast Conversion Between Fahrenheit and Celsius Without a Calculator
If you live in one of the few countries that use the Fahrenheit temperature scale (this could be the United States, Bahamas, Cayman Islands, Liberia, Palau, Federated States of Micronesia, and the Marshall Islands), you cannot be used to trade in Celsius. But that doesn’t mean it doesn’t show up from time to time, like in recipes from other parts of the world or on a trip to Canada … or literally anywhere else not listed above.
You may have learned how to convert Fahrenheit to Celsius (and vice versa) in your elementary school math class, but chances are you don’t remember how to do it today. Fortunately, Quaxon user on Reddit shared an extremely simple method of conversion between degrees Fahrenheit and Celsius in your head without the need for a calculator.
A formula for converting between two temperature scales is not something most of us can do in our heads, but if you just need an accurate estimate, the quaxon formula will do:
C to F: multiply the temperature by 2 and then add 30 (the actual formula multiplies by 1.8, adds 32) eg: 22 C is roughly equal to 74 degrees using my method, the actual conversion is 71.6F to C: Now just work … back, subtract 30 from temp. and then divide by 2 (again, the actual constants of the formula are 1.8 and 32)
As you can see from the quaxon example, this is not an exact result, but if you just need to convert some temperatures when you cook or follow other directions, it works great as a last resort. Or you can do what everyone else is doing and perform the conversion on your phone, computer, or even a dedicated app .
This story was originally published on 6/11/12 and was updated on 6/21/19 to provide more complete and up-to-date information.