Degrees Fahrenheit to degrees Celsius
To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. So 68 °F is 20 °C.
1 degree Fahrenheit = -17.22222222 degrees Celsius
Temperature is the one conversion that cannot be done by multiplying, because the scales have different zero points as well as different step sizes.
Degrees Fahrenheit to degrees Celsius table
| Degrees Fahrenheit (°F) | Degrees Celsius (°C) |
|---|---|
| 0 | -17.77777778 |
| 32 | 0 |
| 50 | 10 |
| 68 | 20 |
| 72 | 22.22222222 |
| 80 | 26.66666667 |
| 98.6 | 37 |
| 100 | 37.77777778 |
| 212 | 100 |
How the conversion works
Temperature is the one conversion here that cannot be done by multiplying, and the reason is that Celsius and Fahrenheit disagree about two things rather than one. Their degrees are different sizes, a Celsius degree being 1.8 Fahrenheit degrees, and their zero points are in different places, Celsius putting zero at the freezing point of water and Fahrenheit putting it 32 degrees lower.
So the conversion has to handle the offset as well as the scale. Going from Fahrenheit to Celsius, subtract 32 first and then multiply by five ninths. Going the other way, multiply by nine fifths and then add 32. Doing those two operations in the wrong order is the single most common mistake, and it is wrong by about 18 degrees.
One value is worth memorising: −40 is the same number on both scales. It is the point where the offset and the scaling cancel, and it is a quick way to check that a conversion is being done correctly in either direction.