Convert Fahrenheit to Celsius instantly. Essential for international travel, cooking and medical reference.
| Unit | Name | Value |
|---|---|---|
| °C | Celsius | -17.222222 |
| K | Kelvin | 255.92778 |
| °R | Rankine | 460.67 |
Subtract 32 then multiply by 5/9. Formula: °C = (°F − 32) × 5/9. Example: (98.6 − 32) × 5/9 = 37°C. Reverse: °F = °C × 9/5 + 32.
| Fahrenheit (°F) | Celsius (°C) | Real-world context |
|---|---|---|
| -40°F | -40°C | Unique crossover — both scales equal |
| 0°F | -17.8°C | US commercial freezer standard |
| 32°F | 0°C | Water freezing point |
| 50°F | 10°C | Cool spring morning |
| 68°F | 20°C | Comfortable room temperature |
| 77°F | 25°C | Warm summer day |
| 98.6°F | 37°C | Normal human body temperature |
| 100.4°F | 38°C | Clinical fever threshold |
| 212°F | 100°C | Boiling point of water |
| 350°F | 177°C | Standard American baking temperature |
| 425°F | 218°C | High-heat roasting temperature |
For fast mental maths: subtract 30 from °F then divide by 2. Example: 70°F → (70−30)÷2 = 20°C (actual: 21.1°C). Error under 2°C — perfect for everyday use.
Lock in: 32°F=0°C, 68°F=20°C, 98.6°F=37°C, 212°F=100°C. Interpolate between them for any other value.
100.4°F = 38°C is the clinical fever line. If a US thermometer shows over 100.4°F, that's a fever in any scale.
Quick oven reverse: halve the °F temp and subtract 10 for approximate °C. 400°F ÷ 2 − 10 = 190°C (actual: 204°C). Close enough for most recipes.
Real professions and situations that need °F to °C conversion
The Fahrenheit scale (symbol: °F) was developed by German physicist Daniel Gabriel Fahrenheit in 1724. His 0°F reference was the coldest temperature achievable with a brine ice mixture; 96°F represented body temperature (later corrected to 98.6°F). Water freezes at 32°F and boils at 212°F.
Fahrenheit's scale dominated scientific use in English-speaking nations for over 200 years. The US is the only major nation still using it for everyday weather, though Fahrenheit remains in some industrial and aviation contexts globally. His scale was likely designed so that the 180-degree span from freezing to boiling (32°F to 212°F) would align with 60-degree subdivisions familiar to contemporary scientists.
The Celsius scale (symbol: °C) was proposed by Swedish astronomer Anders Celsius in 1742. It defines 0°C as the freezing point of water and 100°C as the boiling point at standard atmospheric pressure. The modern definition ties it to the Kelvin scale: 0°C = 273.15 K exactly.
Renamed from "centigrade" to "Celsius" in 1948 at the 9th General Conference on Weights and Measures, the scale has an ironic origin: Celsius's 1742 paper defined 0° as boiling and 100° as freezing — the complete opposite of today. Botanist Carl Linnaeus, a friend of Celsius, inverted the scale to its current intuitive form, but the original inverted version was actually used in Sweden for some years after Celsius's death.
Common use: Fahrenheit-to-Celsius is the most searched temperature conversion globally, driven by international travel to and from the US, worldwide consumption of American media and recipes, and medical communication between US and international health systems. The formula °C = (°F − 32) × 5/9 is worth memorising for anyone navigating the American/international temperature divide.