Celsius to Fahrenheit Converter
Convert °C to °F instantly — exact formula, free, no sign-up required.
Runs entirely in your browser — nothing you type is uploaded or stored.
How to convert Celsius to Fahrenheit
The formula is: °F = (°C × 9/5) + 32. Unlike most conversions on this site, temperature scales are affine (they have an offset as well as a scale factor): Celsius sets 0° at water's freezing point, Fahrenheit sets 32° there instead, and the two scales also disagree on how big one degree is. That's why you can't convert temperature with a single multiplication the way you can convert length or mass — the calculator above runs the full two-step formula rather than a shortcut.
Worked example: a fever reading
A common adult fever threshold is quoted as 38°C in most of the world and 100.4°F in the US — enter 38 above and you'll get exactly 100.4, confirming the two figures really do refer to the same temperature rather than being independently chosen round numbers.
Common mistake: averaging two temperature readings
Because the scales have different zero points, you can't average two temperatures by converting the Celsius average — 10°C and 30°C average to 20°C (68°F), but averaging their Fahrenheit equivalents (50°F and 86°F) gives 68°F too, so simple averaging happens to work here. It breaks down for more complex operations like calculating a percentage temperature change: a "20% increase" in °C does not correspond to a 20% increase in °F, because neither scale's zero point represents "no temperature" the way Kelvin's does. For any calculation involving ratios or percentages of temperature, convert to Kelvin first.
Quick reference
| Celsius | Fahrenheit |
|---|---|
| 0 °C (freezing) | 32 °F |
| 20 °C (room temp) | 68 °F |
| 37 °C (body temp) | 98.6 °F |
| 100 °C (boiling) | 212 °F |
Need Fahrenheit to Celsius instead? Use the swap button above, or convert with °C = (°F − 32) × 5/9.
How to use the converter
Three steps. No account, no download, no waiting.
Confirm the units
This page is pre-set to Celsius to Fahrenheit. Change either dropdown any time to switch units or category — every other EngiConvert category is available from the same selector.
Enter your value
Type a number into the "From" box. The result updates instantly as you type — no button to press.
Copy your result
Use the swap button to flip the conversion, or hit "Copy result" to grab the converted value.
Frequently asked questions
What is the formula for Celsius to Fahrenheit?
°F = (°C × 9/5) + 32.
What temperature is the same in both scales?
−40 degrees is the same value in both Celsius and Fahrenheit (−40 °C = −40 °F) — the one point where the two lines cross.
Why isn't this just a multiplication like other conversions?
Celsius and Fahrenheit have different zero points as well as different scale sizes, so converting between them requires both a multiplication and an addition (an affine transformation), unlike length or mass conversions.
Which countries still use Fahrenheit?
The United States is the main holdout for everyday use; a handful of other territories (including the Bahamas, Belize, Cayman Islands and Palau) also use Fahrenheit alongside or instead of Celsius, while most of the world standardized on Celsius decades ago.
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