ToolPikaHow it works
Unlike length or weight, temperature scales do not all start at zero in the same place, so converting needs an offset as well as a multiplication:
| Conversion | Formula |
|---|---|
| Celsius → Fahrenheit | °F = °C × 9/5 + 32 |
| Fahrenheit → Celsius | °C = (°F − 32) × 5/9 |
| Celsius → Kelvin | K = °C + 273.15 |
| Kelvin → Celsius | °C = K − 273.15 |
| Fahrenheit → Kelvin | K = (°F + 459.67) × 5/9 |
| Kelvin → Fahrenheit | °F = K × 9/5 − 459.67 |
A change of 1 °C is the same size as a change of 1 K, and equal to a change of 1.8 °F. Kelvin is written without the degree sign (300 K, not 300 °K).
Reference temperatures
| Celsius | Fahrenheit | Kelvin | |
|---|---|---|---|
| Absolute zero | −273.15 °C | −459.67 °F | 0 K |
| Celsius and Fahrenheit meet | −40 °C | −40 °F | 233.15 K |
| Water freezes | 0 °C | 32 °F | 273.15 K |
| Room temperature | 20 °C | 68 °F | 293.15 K |
| Normal body temperature | 37 °C | 98.6 °F | 310.15 K |
| Water boils (at sea level) | 100 °C | 212 °F | 373.15 K |
| Moderate oven | 180 °C | 356 °F | 453.15 K |
Examples
- Weather. A forecast of 25 °C is 25 × 1.8 + 32 = 77 °F.
- Cooking. A recipe that says 350 °F needs an oven at about 177 °C; many ovens round it to 180 °C.
- Fever. 38.5 °C is 101.3 °F.
- Science. Room temperature, 25 °C, is 298.15 K.