Fahrenheit to Celsius Converter
Convert fahrenheit (°F) to celsius (°C) instantly, with the exact conversion factor and a table of common values.
How it works
Fahrenheit and celsius measure temperature on scales whose zero points differ, so this is not a simple multiplication — the offset has to be applied as well as the scaling. Multiplying alone gives the wrong answer.
The conversion is applied exactly as defined, with no intermediate rounding. Results are shown to enough decimal places to stay useful for small values without turning large ones into noise.
The formula
Fahrenheit → Celsius
°C = °F × 0.55555556 − 17.7778
Celsius → Fahrenheit
°F = (°C + 17.7778) ÷ 0.55555556
Worked examples
| Scenario | Working | Result |
|---|---|---|
| -40 °F | -40 × 0.55555556 − 17.7778 | -40 °C |
| 0 °F | 0 × 0.55555556 − 17.7778 | -17.7778 °C |
| 32 °F | 32 × 0.55555556 − 17.7778 | 0 °C |
| 50 °F | 50 × 0.55555556 − 17.7778 | 10 °C |
When you'd use it
- Reading a recipe, spec sheet or label written in the other system
- Filling in a form that expects a specific unit
- Checking luggage, shipping or equipment limits
- Coursework and lab reports that require SI units
Common questions
Can I just multiply to convert fahrenheit to celsius?
No — these scales start from different zero points, so a single multiplication gives the wrong answer. You have to apply the offset too. Use the formula shown above, or let this page do it.
Is the conversion exact?
Yes — the relationship between these scales is exact by definition, and the conversion is applied without intermediate rounding. Only the display is rounded, and you can copy the full-precision result.
Why does my answer differ slightly from another converter?
Almost always rounding. Some converters round the factor itself before multiplying, which compounds the error on large values. This one multiplies first and rounds only for display.