Convert any temperature between Celsius, Fahrenheit and Kelvin (plus Rankine and Réaumur) instantly. Type a value, pick its scale, and this free temperature converter shows every other scale with the formula and working, plus a quick reference table.
Temperature conversion formulas
Key temperatures
| Reference point | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Celsius equals Fahrenheit | −40 | −40 | 233.15 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20–25 | 68–77 | 293–298 |
| Normal body temperature | 37 | 98.6 | 310.15 |
| Water boils (1 atm) | 100 | 212 | 373.15 |
| Oven baking | 180 | 356 | 453.15 |
Quick mental trick: to go from °C to °F, double it and add 30 (20 °C → 70 °F, real answer 68 °F). Kelvin has no degree sign and can’t be negative, which makes it the scale used in gas laws and thermodynamics.
Frequently asked questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 (1.8) and add 32. For example 25 °C × 1.8 + 32 = 77 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. For example (98.6 − 32) × 5/9 = 37 °C.
How do I convert Celsius to Kelvin?
Add 273.15. 25 °C is 298.15 K. A temperature difference of 1 °C equals 1 K.
At what temperature are Celsius and Fahrenheit the same?
At −40°: −40 °C equals −40 °F.
Related tools
Free educational tool by HawkInc. Results are calculated in your browser and rounded for display; check critical work by hand or with a second method.