Last updated: May 2026
Convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K) — with quick-tap reference buttons for freezing, body temp, and boiling.
Convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K)
Temperature Reference Table
| Celsius | Fahrenheit | Context |
|---|---|---|
| -40°C | -40°F | Extreme cold (crossover point) |
| 0°C | 32°F | Water freezes |
| 20°C | 68°F | Room temperature |
| 37°C | 98.6°F | Normal body temperature |
| 100°C | 212°F | Water boils (sea level) |
| 180°C | 356°F | Moderate oven |
| 200°C | 392°F | Hot oven / pizza |
Other Unit Converters
Unlike most unit conversions, temperature doesn't convert with a simple multiply — you have to shift the scale first. Celsius and Fahrenheit use different zero points: 0°C is the freezing point of water, while 0°F was originally based on a brine solution. Kelvin starts at absolute zero (−273.15°C), the coldest temperature that can theoretically exist.
The US uses Fahrenheit for weather and cooking. Most of the world uses Celsius. Scientists use Kelvin. If a European recipe says "bake at 180°C" and your oven shows Fahrenheit, you need this converter.
| Convert | Formula | Quick Method |
|---|---|---|
| Celsius → Fahrenheit | (°C × 9/5) + 32 | Double it, subtract 10%, add 32 |
| Fahrenheit → Celsius | (°F − 32) × 5/9 | Subtract 32, then divide by ~1.8 |
| Celsius → Kelvin | °C + 273.15 | Add 273 |
| Kelvin → Celsius | K − 273.15 | Subtract 273 |
| Fahrenheit → Kelvin | (°F − 32) × 5/9 + 273.15 | Convert to °C first, then add 273 |
What temperature is the same in Celsius and Fahrenheit?
−40 degrees. It's the one point where both scales intersect. Above −40, Celsius numbers are always smaller than Fahrenheit numbers. This is occasionally a useful sanity check when doing rough conversions.
What's a quick mental math trick for Celsius to Fahrenheit?
Double the Celsius value and add 30. It's not exact (the real formula multiplies by 1.8 and adds 32), but it gets you within a few degrees for everyday temperatures. Example: 25°C → 25×2=50, +30=80°F. Actual answer is 77°F — close enough for "what should I wear today."
What is normal body temperature in Celsius?
Normal body temperature is 37°C (98.6°F). A temperature above 38°C (100.4°F) is classified as a fever. Modern research suggests average human body temperature has drifted slightly lower than the classic 98.6°F figure, closer to 36.6°C (97.9°F), but 37°C remains the standard clinical reference.
What is absolute zero in Celsius and Fahrenheit?
Absolute zero — the coldest possible temperature — is 0 Kelvin, which equals −273.15°C or −459.67°F. At absolute zero, all molecular motion theoretically stops. It's physically impossible to reach, though scientists have gotten within billionths of a degree in lab conditions.
Why does the US use Fahrenheit instead of Celsius?
The US adopted Fahrenheit before the metric system was standardized, and unlike most countries, never mandated a switch. One argument in its favor: Fahrenheit gives more granularity in the comfortable human temperature range (32°F to 95°F vs 0°C to 35°C), which some find useful for describing daily weather. Science, medicine, and cooking in professional contexts use Celsius even in the US.