Fahrenheit to Celsius
Fahrenheit and Celsius start from different zero points, so this converter applies the full formula rather than a single multiplier.
Converter
Fahrenheit to Celsius at a glance
18 rows| Fahrenheit | Celsius |
|---|---|
| -40 °F | -40 °C |
| -20 °F | -28.88888889 °C |
| -10 °F | -23.33333333 °C |
| 0 °F | -17.77777778 °C |
| 5 °F | -15 °C |
| 10 °F | -12.22222222 °C |
| 15 °F | -9.444444444 °C |
| 20 °F | -6.666666667 °C |
| 25 °F | -3.888888889 °C |
| 30 °F | -1.111111111 °C |
| 35 °F | 1.666666667 °C |
| 37 °F | 2.777777778 °C |
| 40 °F | 4.444444444 °C |
| 50 °F | 10 °C |
| 75 °F | 23.88888889 °C |
| 100 °F | 37.77777778 °C |
| 150 °F | 65.55555556 °C |
| 200 °F | 93.33333333 °C |
Quick pairs
tap to loadWhy people convert fahrenheit to celsius
This direction matters for anyone reading a US recipe, weather report, or oven manual from outside the US. Body temperature is a useful anchor: a normal 98.6°F reading is exactly 37°C, a pairing worth remembering since body temperature comes up in conversation more often than most other Fahrenheit readings. A US thermostat set to 68°F, a common energy-saving winter setting, corresponds to about 20°C, a figure worth knowing when following a heating guide written for a metric-only audience.
Fever thresholds are a related but separate case worth knowing: many US digital thermometers display Fahrenheit by default, while international health guidance, and most doctors outside the US, define a fever starting around 38°C. Converting that threshold shows it sits at 100.4°F, a figure worth having on hand when following care instructions written for a metric audience, so a US reading from a home thermometer can be checked against guidance that was never written with Fahrenheit in mind.
Popular temperature conversions
2 pagesHow the fahrenheit to celsius conversion works
Fahrenheit and Celsius place their zero points at different temperatures and size their degrees differently, so this conversion needs a subtraction before the multiplication, not a single multiplier.
Subtract 32 from the Fahrenheit value, then multiply by 5/9 (0.5555555556):
Celsius = (Fahrenheit - 32) × 5/9
Worked examples: (32°F - 32) × 5/9 = 0°C, (98.6°F - 32) × 5/9 = 37°C, and (68°F - 32) × 5/9 = 20°C, covering freezing, normal body temperature, and a mild indoor setting.
Because 5/9 is a repeating decimal (0.5555...), it is worth carrying several digits, or better, using the fraction directly, rather than rounding to 0.56. That rounding is harmless for a single mild temperature but grows noticeably for larger or more extreme Fahrenheit readings, where a small per-degree error compounds.
The most common mistake is multiplying by 5/9 before subtracting 32, instead of after. A second mistake is inverting the fraction and multiplying by 9/5 instead of 5/9, which is the step used going the other way, from Celsius to Fahrenheit, and swapping the two fractions reliably produces a wrong answer in both directions.
Questions
What is the formula for Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit reading, then multiply by 5/9 (0.5555555556): Celsius = (Fahrenheit - 32) × 5/9. The subtraction has to happen first.
How do I convert Celsius back to Fahrenheit?
Reverse both steps: multiply by 9/5 (1.8) first, then add 32. The swap button on this page flips the two units without retyping the value, useful for double-checking a result.
Is there a fast mental shortcut for Fahrenheit to Celsius?
Subtracting 30 from the Fahrenheit value and then halving the result gives a workable estimate for everyday temperatures, within a degree or two of the exact answer across most normal weather ranges.
Why does 98.6 degrees Fahrenheit convert to exactly 37 degrees Celsius?
It isn't a coincidence: 98.6°F was originally derived by converting 37°C, the commonly cited average body temperature, using the exact formula, so the two values match precisely rather than approximately.
What does a cold reading like -4 degrees Fahrenheit equal in Celsius?
-4°F works out to -20°C: subtracting 32 gives -36, and multiplying by 5/9 gives exactly -20, a good example of the formula handling negative readings without any special adjustment.
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