Temperature Converter
Celsius to Fahrenheit, Fahrenheit to Celsius, and Kelvin for scientific work. Temperature is the one conversion that cannot be done with a simple multiplier, because the scales have different zero points — this tool applies the correct formula in both directions.
Last updated — conversions use exact unit definitions, so results stay accurate.
| Unit | Value |
|---|
How it works
Temperature scales do not share a zero point, so converting needs both a scaling factor and an offset. Celsius to Fahrenheit is °F = (°C × 9/5) + 32; Fahrenheit to Celsius is °C = (°F − 32) × 5/9. That offset of 32 is why 20 °C is 68 °F rather than 36 °F, and why doubling a Celsius temperature does not double its Fahrenheit value.
Kelvin is the SI absolute scale. It has the same step size as Celsius but starts at absolute zero, so K = °C + 273.15. There is no degree symbol in Kelvin and no negative values, which makes it the right scale for anything involving gas laws, thermodynamics or cryogenics.
Celsius and Fahrenheit cross at −40, the one point where both scales read the same: −40 °C = −40 °F. It is a handy sanity check when you suspect a sign error.
For cooking, note that oven temperatures are quoted differently by region: American recipes use °F, most of the world uses °C, and British recipes often use gas marks. Our cooking converter includes an oven temperature chart covering all three.
Temperature reference points
| Celsius | Fahrenheit | Kelvin | What it is |
|---|---|---|---|
| −273.15 °C | −459.67 °F | 0 K | Absolute zero |
| −40 °C | −40 °F | 233.15 K | Where both scales meet |
| 0 °C | 32 °F | 273.15 K | Water freezes |
| 20 °C | 68 °F | 293.15 K | Room temperature |
| 37 °C | 98.6 °F | 310.15 K | Human body temperature |
| 100 °C | 212 °F | 373.15 K | Water boils at sea level |
| 180 °C | 356 °F | 453.15 K | Standard oven (moderate) |
| 220 °C | 428 °F | 493.15 K | Hot oven (roasting) |
Frequently asked questions
What is the formula to convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5, then add 32: °F = (°C × 9/5) + 32. So 100 °C × 9/5 = 180, plus 32 equals 212 °F. For a quick mental estimate, double the Celsius value and add 30 — accurate to within a few degrees around room temperature.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value, then multiply by 5/9: °C = (°F − 32) × 5/9. So 98.6 °F − 32 = 66.6, times 5/9 equals 37 °C. The rough mental version is to subtract 30 and halve the result.
At what temperature are Celsius and Fahrenheit equal?
At −40 degrees. It is the only point where the two scales read identically, which makes it a useful check when you want to confirm a conversion formula is being applied correctly.
Why does water boil at different temperatures?
The boiling point depends on air pressure. At sea level water boils at 100 °C, but at 2,000 m altitude it boils at about 93 °C, and in a pressure cooker it can exceed 120 °C. The converter uses the standard scale; it does not adjust for your local pressure or altitude.
When should I use Kelvin?
Use Kelvin for scientific and engineering work, where absolute temperature matters — gas laws, radiation, cryogenics, thermodynamics. It has no negative values, so ratios between temperatures are meaningful, which is not true of Celsius or Fahrenheit.