Temperature Converter
The formulas
Unlike other units, temperature scales do not share the same zero, so converting needs an offset as well as a factor:
- °F = °C × 9/5 + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
Example: 20 °C × 1.8 = 36, plus 32 = 68 °F. In the other direction, 98.6 °F − 32 = 66.6, × 5/9 = 37 °C.
Reference temperatures
| Celsius | Fahrenheit | Kelvin | |
|---|---|---|---|
| Absolute zero | −273.15 °C | −459.67 °F | 0 K |
| Same value on both scales | −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 (sea level) | 100 °C | 212 °F | 373.15 K |
Oven temperatures
Recipes rarely use exact conversions; they round to the nearest common oven setting:
| Celsius | Exact °F | Usual recipe value |
|---|---|---|
| 160 °C | 320 °F | 325 °F |
| 180 °C | 356 °F | 350 °F |
| 200 °C | 392 °F | 400 °F |
| 220 °C | 428 °F | 425 °F |
Fan (convection) ovens usually need about 20 °C less than the temperature given for a conventional oven.
Good to know
- Kelvin is written without a degree sign (300 K, not 300 °K) and is used in science because it starts at absolute zero.
- A temperature difference converts without the offset: a rise of 10 °C is a rise of 18 °F, not 50 °F.
- Quick estimate from °C to °F: double and add 30 (20 °C → 70 °F, exact 68 °F). It works best between 0 and 30 °C.
Frequently Asked Questions
At what temperature are Celsius and Fahrenheit equal?
At −40. −40 °C is exactly −40 °F.
Is 38 °C a fever?
38 °C equals 100.4 °F, the threshold generally used to define a fever in adults. Seek medical advice if a fever is high or persistent.
Why can't Kelvin be negative?
0 K is absolute zero, the lowest temperature physically possible, so the Kelvin scale has no negative values.