EngineeringFormulaTemperature Conversion
Convert °F to °C
1 °F = -17.222 °C
Unlike every other pair on this page, this is an affine conversion, not a pure multiplier - it needs both a scale factor and an offset (°C = (°F − 32) × 5/9), which is why a naive unit-multiplier approach gets it wrong.
°C = (°F − 32) × 5/9, and the reverse, °F = °C × 9/5 + 32. The 5/9 (or 9/5) factor comes from the two scales dividing the same physical range - water's freezing-to-boiling interval - into a different number of degrees: 100 on the Celsius scale, 180 on the Fahrenheit scale.
Body temperature, 98.6°F, is 37°C; a hot summer day at 100°F is about 37.8°C - coincidentally close in value despite being different quantities.
Reference Table
| fahrenheit (°F) | celsius (°C) |
|---|---|
| 1 | -17.222 |
| 5 | -15 |
| 10 | -12.222 |
| 25 | -3.8889 |
| 50 | 10 |
| 100 | 37.778 |
Used In These Calculators
Frequently Asked Questions
Why can't temperature be converted the same way as other units on this page?
Every other conversion on this site is a pure ratio (multiply by a factor). Fahrenheit and Celsius don't share a common zero point - 0°F isn't the same physical temperature as 0°C - so the conversion needs an additive offset in addition to a scale factor. Kelvin, by contrast, does share Celsius's scale and only needs an offset (K = °C + 273.15), with no multiplier at all.
Is there a temperature where Fahrenheit and Celsius show the same number?
Yes - exactly one: −40°. Solving (F − 32) × 5/9 = F for F gives F = −40, so −40°F and −40°C are the same physical temperature, the single point where the two scales' numeric values coincide.
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