Celsius to Fahrenheit Converter Guide: Formulas & Temperature Tips
Quick Answer
- *°F = (°C × 9/5) + 32. Multiply by 1.8, then add 32.
- *°C = (°F − 32) × 5/9. Subtract 32, then multiply by 0.5556.
- *Quick trick: double the Celsius and add 30 for a rough estimate.
- *The two scales are equal at −40°. Water freezes at 0°C / 32°F.
The Conversion Formulas
Two formulas handle every temperature conversion between Celsius and Fahrenheit. The “9/5” ratio exists because each Fahrenheit degree is smaller than a Celsius degree — there are 180 Fahrenheit degrees between freezing and boiling, but only 100 Celsius degrees. 180/100 simplifies to 9/5, or 1.8.
Celsius to Fahrenheit: °F = (°C × 1.8) + 32
Fahrenheit to Celsius:°C = (°F − 32) / 1.8
The +32 offset accounts for the different zero points. Fahrenheit set 32°F as water’s freezing point; Celsius set 0°C.
Temperature Reference Chart
| Celsius | Fahrenheit | Context |
|---|---|---|
| −40°C | −40°F | Where both scales meet |
| −18°C | 0°F | Fahrenheit’s zero point |
| 0°C | 32°F | Water freezes |
| 10°C | 50°F | Cool autumn day |
| 20°C | 68°F | Room temperature |
| 25°C | 77°F | Warm spring day |
| 30°C | 86°F | Hot summer day |
| 37°C | 98.6°F | Normal body temperature |
| 100°C | 212°F | Water boils (at sea level) |
| 180°C | 356°F | Common baking temperature |
History of the Two Scales
Daniel Gabriel Fahrenheit, a German physicist working in Amsterdam, created his scale in 1724. He set 0°F as the temperature of a brine solution (the coldest he could reliably produce), 32°F as ice melting, and 96°F as body temperature. The scale was later adjusted slightly, which is why normal body temperature ended up at 98.6°F rather than a round number.
Anders Celsius, a Swedish astronomer, proposed his scale in 1742. Originally, he set 0° as boiling and 100° as freezing — inverted from what we use today. After his death, fellow Swedish scientists flipped it. By the mid-20th century, most of the world had adopted the Celsius scale as part of the metric system.
When Each Scale Is Used
Fahrenheit is the daily standard in the United States, its territories, the Bahamas, the Cayman Islands, and Palau. American weather forecasts, oven dials, thermostats, and body temperature readings all use Fahrenheit.
Celsius is used by the rest of the world for weather, cooking (in many countries), and general temperature references. Science uses Celsius (or Kelvin) universally, even in the US. Medical research often reports temperatures in Celsius.
Quick Mental Math Tricks
Double and add 30:For everyday temperatures (0–30°C), double the Celsius and add 30. For 22°C: 44 + 30 = 74°F. The exact answer is 71.6°F. Not perfect, but close enough to decide whether to bring a jacket.
Memorize anchor points:If you remember that 0°C = 32°F, 10°C = 50°F, 20°C = 68°F, and 30°C = 86°F, you can interpolate between them. Each 10°C step equals 18°F, so each 5°C is 9°F.
Cooking Temperature Conversions
Oven temperatures trip people up constantly. British and Australian recipes use Celsius. American recipes use Fahrenheit. Many European recipes also reference “Gas Mark” settings.
| Description | Celsius | Fahrenheit |
|---|---|---|
| Very low oven | 120°C | 250°F |
| Low oven | 150°C | 300°F |
| Moderate oven | 180°C | 350°F |
| Hot oven | 200°C | 400°F |
| Very hot oven | 230°C | 450°F |
| Broil/grill | 260°C | 500°F |
Convert temperatures instantly between Celsius and Fahrenheit
Use our free Temperature Converter →Frequently Asked Questions
What is the formula to convert Celsius to Fahrenheit?
The formula is: °F = (°C × 9/5) + 32. Multiply the Celsius temperature by 1.8, then add 32. For example, 25°C × 1.8 + 32 = 77°F.
What is the formula to convert Fahrenheit to Celsius?
The formula is: °C = (°F − 32) × 5/9. Subtract 32 from the Fahrenheit temperature, then multiply by 0.5556. For example, (72°F − 32) × 5/9 = 22.2°C.
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit are equal at −40 degrees. Both −40°C and −40°F represent the same temperature. This is the only point where the two scales intersect.
Why does the US use Fahrenheit?
The US adopted Fahrenheit when it was the standard in the English-speaking world. When most countries switched to Celsius in the 1960s–1970s, the US chose not to mandate the change. Today, only the US and a few small nations use Fahrenheit daily.
Is there a quick trick to estimate Celsius to Fahrenheit?
Double the Celsius value and add 30. This gives a rough Fahrenheit estimate accurate within a few degrees for everyday temperatures. For example, 20°C → 40 + 30 = 70°F (exact: 68°F).