The two most common temperature scales worldwide, converted with the internationally defined exact relationship between them.
How it works
Multiplying Celsius by 9/5 and adding 32 gives Fahrenheit; subtracting 32 from Fahrenheit and multiplying by 5/9 gives Celsius back.
What this does not include
This does not include Kelvin — for that, use this site’s full temperature converter, which covers all three scales on one page.
How to use this calculator
- Enter a value in either Celsius or Fahrenheit — the other field fills in automatically.
A worked example
25°C → (25 × 9/5) + 32 = 77°F. −40°C → (−40 × 9/5) + 32 = −40°F — the one point where both scales agree.
What the formula does
| Term | Role |
|---|---|
| × 9/5 | Scales for Fahrenheit’s smaller degree size |
| + 32 | Shifts for Fahrenheit’s different zero point |
Edge cases worth knowing
−40 is the single temperature where Celsius and Fahrenheit read the same number — below or above it, the two scales diverge further apart in either direction.
0°C (freezing) is 32°F, not 0°F — a frequent point of confusion for anyone used to only one of the two scales.
Frequently asked questions
Why do 0°C and 32°F both mean freezing?
The two scales use different zero points and different-sized degrees — the offset and scaling factor in the formula account for both differences at once.
What temperature is the same on both scales?
−40 degrees — the one point where Celsius and Fahrenheit numerically coincide.
Which countries use Fahrenheit?
The United States is the primary country still using Fahrenheit for everyday temperature; most of the rest of the world uses Celsius.
