Degrees Fahrenheit to Degrees Celsius Converter
Convert degrees fahrenheit (°F) to degrees celsius (°C) with the calculator below. Enter a value in either field for an instant result.
20 °F equals -6.666666667 °C.
Degrees Fahrenheit to Degrees Celsius Conversion Table
Use these common values as a quick reference.
| Degrees Fahrenheit (°F) | Degrees Celsius (°C) |
|---|---|
| -40 °F | -40 °C |
| 0 °F | -17.77777778 °C |
| 10 °F | -12.22222222 °C |
| 20 °F | -6.666666667 °C |
| 32 °F | 0 °C |
| 50 °F | 10 °C |
| 100 °F | 37.77777778 °C |
| 212 °F | 100 °C |
How to Convert Fahrenheit to Celsius
Conversion: 1 °F = -17.22222222 °C.
Formula: °C = (°F − 32) × 5/9
- Enter the fahrenheit value.
- Apply the conversion formula shown above.
- Round the result only as much as your use requires.
Example: 20 °F = -6.666666667 °C.
Understanding the Fahrenheit to Celsius Conversion
Fahrenheit and Celsius use different reference points. A correct conversion therefore applies the full scale formula rather than a simple one-step multiplier.
Temperature conversion is different from most unit conversion because the scales have different zero points as well as different interval sizes. That is why an offset must be applied in addition to multiplication or division.
Fahrenheit is commonly used for everyday temperatures in the United States, while Celsius is commonly used for everyday temperatures in most countries. Converting between them makes measurements easier to compare without changing the quantity being described.
Worked Fahrenheit to Celsius Examples
These examples show how the conversion works for several practical values.
- -40 °F: Apply °C = (°F − 32) × 5/9 to get -40 °C.
- 20 °F: Apply °C = (°F − 32) × 5/9 to get -6.666666667 °C.
- 100 °F: Apply °C = (°F − 32) × 5/9 to get 37.77777778 °C.
Accuracy, Precision and Rounding
Everyday Units applies the complete temperature-scale formula, including its required offset.
The calculator normally shows up to ten significant digits and removes unnecessary trailing zeros. This balances accuracy with readability. If the result will be used in engineering, science, medicine, trade or another precision-sensitive setting, follow the rounding and tolerance rules required for that specific use.
Common mistakes to avoid
- Do not treat temperature as a factor-only conversion; the offset in °C = (°F − 32) × 5/9 is required.
- Do not round the conversion factor before completing the calculation.
- Keep the unit symbol beside the number so the result cannot be mistaken for another measurement.
About the Units
Fahrenheit (°F)
Definition: Fahrenheit is a temperature scale where water freezes at 32 °F and boils at about 212 °F at standard pressure.
History and origin: The scale was proposed by Daniel Gabriel Fahrenheit.
Current use: This unit is commonly used for everyday temperatures in the United States.
Celsius (°C)
Definition: Celsius is a temperature scale where water freezes at 0 °C and boils at about 100 °C at standard pressure.
History and origin: The scale is named for Swedish astronomer Anders Celsius.
Current use: This unit is commonly used for everyday temperatures in most countries.
Frequently Asked Questions
How many degrees celsius are in one fahrenheit?
One fahrenheit is -17.22222222 °C. The calculator uses this relationship for every value entered.
What is the reverse celsius to fahrenheit conversion?
One celsius equals 33.8 °F. Use the reverse-conversion link below to open that calculator directly.
Can I convert decimal and very small values?
Yes. Enter integers, decimals, or very small values in either field. Results use sensible precision, with scientific notation only when it improves readability.
How should I round the result?
Keep the full calculator result during intermediate work, then round once at the end. Everyday estimates may need only two or three decimal places, while technical work may require more significant digits.
Is the fahrenheit to celsius conversion accurate?
The calculation uses the centralized conversion constant shown on this page. Everyday Units converts through the category’s base unit and keeps more precision internally than is normally needed for display.
How This Calculator Works
All calculations happen locally in your browser. No conversion request is sent to an external service. The same centralized unit definitions power the calculator, formula, examples and tables, which helps keep the figures consistent across every related page. Read our conversion methodology and sources for standards, assumptions and rounding details.
For a quick check, compare the forward and reverse relationships above: converting a value to °C and back to °F should return the original measurement, apart from normal display rounding.