Celsius to Fahrenheit Converter
Convert Celsius to Fahrenheit and back. Enter a temperature in °C (or switch to °F) to get the other scale plus Kelvin, using F = C × 9/5 + 32.
Example: with Temperature 37 · Direction °C → °F → Result: 98.6 °F.
- In Kelvin310.15 K
- Formula37 × 9/5 + 32 = 98.6 °F
Computed by the calculator below using its default values. Change any input to see your own numbers.
F = C × 9/5 + 32. A Celsius degree is 1.8 times as big as a Fahrenheit degree, and the +32 sets the freezing point of water. The scales meet at −40°.
Two offsets, one slope
Celsius and Fahrenheit disagree on two things: where zero sits and how big a degree is. Fahrenheit puts water freezing at 32 and boiling at 212, a span of 180 degrees, while Celsius uses 0 and 100. That makes each Celsius degree 180/100 = 1.8 Fahrenheit degrees, which is the 9/5 factor.
So the conversion scales by 9/5 and then shifts by 32. Skip either step and you land far off. The single point where the two scales cross is −40 degrees, a handy check: if your formula does not return −40 °F for −40 °C, something is wrong.
How it’s calculated
F = C × 9/5 + 32; C = (F − 32) × 5/9. Kelvin = C + 273.15. The 9/5 slope reflects that a Celsius degree is 1.8 times as large as a Fahrenheit degree, and the +32 offset sets the freezing point of water.
Standard thermometric scales with no correction for pressure or instrument. Converts a temperature, not a temperature difference.
Celsius to Fahrenheit reference
| Celsius | Fahrenheit | Note |
|---|---|---|
| -40 °C | -40 °F | scales meet |
| 0 °C | 32 °F | water freezes |
| 20 °C | 68 °F | room temperature |
| 37 °C | 98.6 °F | body temperature |
| 100 °C | 212 °F | water boils |
Computed as F = C × 9/5 + 32. The scales coincide at −40 degrees.
Common mistakes
- Adding 32 before multiplying — the ×9/5 comes first, then +32.
- Using 1.8 loosely and dropping the +32 offset entirely.
- Confusing a temperature with a change in temperature: a rise of 5 °C is a rise of 9 °F, not 41 °F.
Frequently asked questions
What is the Celsius to Fahrenheit formula?
F = C × 9/5 + 32. Multiply Celsius by nine-fifths (1.8), then add 32.
What is 37 °C in Fahrenheit?
98.6 °F, normal human body temperature. 37 × 9/5 = 66.6, and 66.6 + 32 = 98.6.
How do I convert Fahrenheit back to Celsius?
Reverse the steps: C = (F − 32) × 5/9. Subtract 32 first, then multiply by five-ninths.
Where do the two scales meet?
At −40 degrees. Minus 40 Celsius equals minus 40 Fahrenheit, the one temperature that reads the same on both scales.