Fahrenheit to Celsius Converter
Convert fahrenheit (°F) to celsius (°C) using documented conversion factors. Includes interactive calculations, conversion formula, worked steps, and common reference tables.
Live Interactive Calculator
°C = (°F − 32) × 5/9Conversion Formula
To convert from fahrenheit to celsius, apply the mathematical formula:
Where °F represents fahrenheit and °C represents celsius.
Conversion Factor
The base relationship defined under primary measurement standards:
Reference: NIST SP 811
Understanding Temperature Scale Conversions
Unlike length or weight conversions, which are purely multiplicative ratios, temperature conversions between Fahrenheit and Celsius require an affine transformation (both multiplication and an offset) because their zero points are defined differently:
The difference between freezing and boiling is 100 degrees on the Celsius scale and 180 degrees on the Fahrenheit scale. This yields the exact step ratio:
To convert from Celsius to Fahrenheit, multiply the Celsius temperature by 1.8 (or 9/5) and then add the 32° offset. To convert from Fahrenheit to Celsius, subtract the 32° offset first and then multiply by 5/9 (approximately 0.5556).
How to Convert Fahrenheit to Celsius
Converting measurements between fahrenheit and celsius follows a structured calculation process:
- Identify the quantity in fahrenheit (°F) that you wish to convert.
- Apply the temperature scale formula:
°C = (°F − 32) × 5/9. - The resulting value is the equivalent amount expressed in celsius (°C).
Common Fahrenheit to Celsius Reference Table
Frequently referenced values calculated using documented measurement conversion factors.
| Fahrenheit (°F) | Celsius (°C) | Arithmetic Expression |
|---|---|---|
| -40 °F | -40 °C | (-40 − 32) × 5/9 |
| 0 °F | -17.777778 °C | (0 − 32) × 5/9 |
| 10 °F | -12.222222 °C | (10 − 32) × 5/9 |
| 20 °F | -6.666667 °C | (20 − 32) × 5/9 |
| 32 °F | 0 °C | (32 − 32) × 5/9 |
| 40 °F | 4.444444 °C | (40 − 32) × 5/9 |
| 50 °F | 10 °C | (50 − 32) × 5/9 |
| 60 °F | 15.555556 °C | (60 − 32) × 5/9 |
| 68 °F | 20 °C | (68 − 32) × 5/9 |
| 70 °F | 21.111111 °C | (70 − 32) × 5/9 |
| 72 °F | 22.222222 °C | (72 − 32) × 5/9 |
| 75 °F | 23.888889 °C | (75 − 32) × 5/9 |
| 80 °F | 26.666667 °C | (80 − 32) × 5/9 |
| 90 °F | 32.222222 °C | (90 − 32) × 5/9 |
| 98.6 °F | 37 °C | (98.6 − 32) × 5/9 |
| 100 °F | 37.777778 °C | (100 − 32) × 5/9 |
| 212 °F | 100 °C | (212 − 32) × 5/9 |
| 350 °F | 176.666667 °C | (350 − 32) × 5/9 |
| 400 °F | 204.444444 °C | (400 − 32) × 5/9 |
Worked Calculation Examples
Practical step-by-step calculations showing how to convert fahrenheit to celsius with exact mathematical equations.
Application context: Freezing point of water (0 °C)
Application context: Standard indoor room temperature (20 °C)
Application context: Normal human core body temperature (37 °C)
Application context: Boiling point of water at sea level (100 °C)
Application context: Common baking oven temperature (≈ 176.67 °C)
About the Units
Authoritative technical specifications and historical definitions for both units.
Fahrenheit (°F)
The Fahrenheit scale sets the freezing point of water at 32 °F and boiling point at 212 °F under standard atmospheric pressure. Primarily used in the United States.
Celsius (°C)
The Celsius temperature scale is defined such that 0 °C is 273.15 K (the approximate freezing point of water) and 100 °C is 373.15 K. An interval of 1 °C equals 1 Kelvin.
Need to convert Celsius back to Fahrenheit?
Reverse Formula: °F = (°C × 9/5) + 32
Related Temperature Converters
Contextual conversions related to this pair within the measurement graph.