Temperature converters
Convert between the Celsius and Fahrenheit scales. Type a value and get the result instantly, with the formula and a note on body temperature ranges.
About temperature conversion
Three temperature scales are in everyday and scientific use. Celsius is the standard almost everywhere: water freezes at 0 °C and boils at 100 °C, body temperature is about 37 °C. Fahrenheit is used in the United States and a handful of other places: freezing is 32 °F, boiling 212 °F, body temperature 98.6 °F. Kelvin is the SI unit for science: the same step size as Celsius, but counted from absolute zero, so 0 °C is 273.15 K.
Unlike length or weight, temperature scales do not share a zero point, so converting is not a simple multiplication. Celsius to Fahrenheit multiplies by 9/5 and then adds 32; Fahrenheit to Celsius subtracts 32 first and then multiplies by 5/9; Celsius to Kelvin just adds 273.15.
Conversion factors at a glance
| From | To | Formula |
|---|---|---|
| °C | °F | °F = °C × 9/5 + 32 |
| °F | °C | °C = (°F − 32) × 5/9 |
| °C | K | K = °C + 273.15 |
| K | °C | °C = K − 273.15 |
Which converter do I need?
Body temperature and fever. Use Celsius to Fahrenheit or the reverse; the pages for values between 36 and 43 °C show a note on whether the reading is in the normal or fever range. Cooking. Oven settings in American recipes are in Fahrenheit (350 °F is 177 °C); European ovens use Celsius. Weather. Forecasts abroad are the most common reason people convert: 20 °C is a pleasant 68 °F, 30 °C is a hot 86 °F, −10 °C is 14 °F. Science and photography. Gas-law calculations and colour temperature use kelvin.
Quick mental math
Celsius to Fahrenheit: double the number and add 30 — 20 °C → 70 °F (exact answer 68). Fahrenheit to Celsius: subtract 30 and halve — 80 °F → 25 °C (exact 26.7). The two scales meet at −40, where −40 °C = −40 °F.
Common questions
What is normal body temperature? About 36.5–37.5 °C (97.7–99.5 °F); a fever is usually defined as 38 °C (100.4 °F) or higher. What temperature is a hot day? 30 °C is 86 °F; 35 °C (95 °F) is heat-wave territory. How cold is a freezer? −18 °C, which is 0 °F — the two scales' zero points happen to line up there. Why is Fahrenheit still used? Mostly habit: the US never completed metrication, and weather and body-temperature intuition are hard to relearn.