A temperature converter moves between Celsius, Fahrenheit and Kelvin - scales that differ in both their zero point and their step size. Fahrenheit, Celsius, Kelvin, and Rankine - exact formulas with the fractions kept exact, the −40 crossover explained, and absolute zero treated honestly.
| Temperature | Equals |
|---|---|
| 0 °C (water freezes) | 32 °F |
| 100 °C (water boils) | 212 °F |
| 37 °C (body temp) | 98.6 °F |
| 20 °C (room temp) | 68 °F |
| -40 °C (the crossover) | -40 °F |
| 0 K (absolute zero) | -273.15 °C |
| 350 °F (common oven) | 176.6666667 °C |
Table computed by the same engine as the tool above.
Fahrenheit to Celsius: °C = (°F − 32) × 5/9. Celsius to Fahrenheit: °F = °C × 9/5 + 32. Kelvin is Celsius shifted so zero sits at absolute zero: K = °C + 273.15 exactly. Rankine does the same for Fahrenheit: °R = °F + 459.67. These are exact by definition - the 5/9 is a true fraction, not 0.5556 - which is why converting 100°C gives exactly 212°F, not 211.99.
The two scales cross where F = C: solving x = x × 9/5 + 32 gives x = −40. So −40°F and −40°C are the same temperature - the one point where the scales agree, and a handy sanity check for any converter (including this one - try it above).
Kelvin is the SI base unit for temperature, written without a degree sign (300 K, not 300°K). Its zero is absolute zero (−273.15°C) - the floor below which temperature cannot go - so negative Kelvin values aren't physically meaningful for ordinary matter, and this converter says so rather than silently returning one. Cooking temperatures have their own chart including gas marks; wind chill and heat index - what temperature feels like - are a separate calculator using the NWS formulas.
Multiply by 1.8 and add 32. Twenty-five degrees Celsius is 77 Fahrenheit. Note that this is not a simple multiplication, because the two scales have different zero points.
Minus 40. It is the single point where the two scales cross, which is why -40°C and -40°F are the same temperature.
Each of these has its own page with the exact factor, a reference table and the working shown. The converter above handles any of them too - these exist so the specific answer is one click rather than a search.