Converters
Celsius to Fahrenheit
The formula is (°C × 9/5) + 32. Multiply your Celsius value by 1.8, then add 32. This guide covers the formula, a mental math shortcut, and a full reference chart for common temperatures.
The formula
°F = (°C × 9/5) + 32
Or equivalently: °F = (°C × 1.8) + 32
The 9/5 factor accounts for the different step sizes between the two scales. A one-degree change in Celsius equals a 1.8-degree change in Fahrenheit. The +32 shifts the starting point — because water freezes at 0°C but 32°F.
Three worked examples
0°C→32°FWater's freezing point22°C→71.6°FComfortable room temperature100°C→212°FWater's boiling pointMental math shortcut
When you don't have a calculator: double the Celsius temperature, subtract 10% of that result, then add 32.
25°C → double = 50 → subtract 10% = 45 → +32 = 77°F
30°C → double = 60 → subtract 10% = 54 → +32 = 86°F
This works exactly because 9/5 = 1.8, and "double minus 10%" gives 2 − 0.2 = 1.8. No approximation — it's the real formula, just in a more mental-arithmetic-friendly order.
When you actually need this conversion
The most common situation is weather. You're in the US and the forecast says 95°F. That's hot — but how hot? Convert it: (95 − 32) × 5/9 = 35°C. A hot summer day anywhere in the world.
The second most common: recipes. A European recipe says bake at 180°C. Your oven is labeled in Fahrenheit. That's 356°F — call it 350°F and you're close enough. Most ovens aren't precise to 6 degrees anyway.
The third: medicine. Normal body temperature is 37°C or 98.6°F. A fever starts around 38°C / 100.4°F. Knowing both helps when dealing with US and non-US healthcare providers or medication instructions.
Celsius to Fahrenheit chart
| °C | °F | Context |
|---|---|---|
| -40 | -40 | Scales intersect |
| -18 | -0.4 | Cold US winter |
| 0 | 32 | Water freezes |
| 10 | 50 | Chilly morning |
| 15 | 59 | Cool day |
| 20 | 68 | Comfortable room |
| 25 | 77 | Warm day |
| 30 | 86 | Hot summer day |
| 37 | 98.6 | Body temperature |
| 40 | 104 | Fever / dangerous heat |
| 100 | 212 | Water boils |
| 180 | 356 | Moderate oven |
| 220 | 428 | Very hot oven |
Convert any temperature instantly
Type in Celsius, Fahrenheit, or Kelvin — all three update as you type.
Temperature Converter →Frequently asked questions
What is the formula to convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (or 1.8), then add 32. Written out: °F = (°C × 9/5) + 32. For example, 20°C = (20 × 1.8) + 32 = 36 + 32 = 68°F.
What is 37°C in Fahrenheit?
37°C is 98.6°F. This is normal human body temperature. The calculation: (37 × 9/5) + 32 = 66.6 + 32 = 98.6°F.
What is 100°C in Fahrenheit?
100°C is 212°F — the boiling point of water at sea level. The calculation: (100 × 1.8) + 32 = 180 + 32 = 212°F.
Is there a temperature that is the same in Celsius and Fahrenheit?
Yes: −40°. Both scales read −40 at that exact point. It's the one temperature where the Celsius and Fahrenheit values are identical. You can verify: (−40 × 1.8) + 32 = −72 + 32 = −40.
What is the quick mental math trick for Celsius to Fahrenheit?
Double the Celsius temperature, subtract 10% of that number, then add 32. Example: 25°C → double = 50, subtract 10% (5) = 45, add 32 = 77°F. The actual answer is 77°F exactly. This works because 9/5 = 1.8, and 2 − 0.2 = 1.8.
Why do the US and UK use different temperature scales?
The US adopted Fahrenheit in the 18th century before Celsius was standardized, and it stuck. The UK switched to Celsius as part of metrication in the 1960s and 70s. Most countries now use Celsius for weather, medicine, and science, while the US remains the main holdout for Fahrenheit in everyday use.