How to Convert Celsius to Fahrenheit
The conversion formula is: °F = (°C × 9/5) + 32, or equivalently °F = (°C × 1.8) + 32. You multiply the Celsius value by 1.8 (because the Fahrenheit scale has 1.8 degrees per 1 Celsius degree), then add 32 (because 0°C = 32°F, not 0°F).
Quick mental trick: Double the Celsius value, subtract 10%, then add 32. For example, 20°C → 40, subtract 4 → 36, add 32 → 68°F. (Exact answer: 68°F ✓)
Celsius to Fahrenheit Reference Table
| Celsius (°C) | Fahrenheit (°F) | Meaning |
|---|---|---|
| -40°C | -40°F | C and F are equal here |
| -20°C | -4°F | Very cold winter |
| -10°C | 14°F | Arctic conditions |
| 0°C | 32°F | Water freezes |
| 10°C | 50°F | Cool autumn day |
| 15°C | 59°F | Mild spring |
| 20°C | 68°F | Room temperature |
| 25°C | 77°F | Warm, comfortable |
| 30°C | 86°F | Hot summer day |
| 37°C | 98.6°F | Human body temperature |
| 40°C | 104°F | Fever / heat wave |
| 100°C | 212°F | Water boils (sea level) |
| 180°C | 356°F | Oven — moderate |
| 220°C | 428°F | Oven — hot |
History of Celsius and Fahrenheit
Daniel Gabriel Fahrenheit (1686–1736), a Polish-German physicist, invented the mercury thermometer and the Fahrenheit scale in 1724. He set 0°F at the coldest brine mixture he could create (salt + ice + water), and 96°F at body temperature. (Later recalibrations placed body temperature at 98.6°F.)
Anders Celsius (1701–1744), a Swedish astronomer, proposed the centigrade scale in 1742 — originally with 0 at boiling and 100 at freezing (inverted!). After his death, Carl Linnaeus reversed it to the familiar form: 0°C = freezing, 100°C = boiling. The scale was renamed "Celsius" in 1948. Today, Celsius is used by virtually every country except the United States, Belize, and a handful of territories.