-40 °F = -40 °C
-40 degrees Fahrenheit is -40 degrees Celsius exactly.
- Exact
- -40 °C
- Rounded
- -40 °C
- Formula
- (-40 − 32) × 5/9
Convert any other temperature
Type in either box; the other follows, and the scale moves with it. Works for decimals and, for temperatures, numbers below zero.
Around -40 °F
Fahrenheit to Celsius for the whole numbers either side of -40, rounded to one decimal place. Each row opens its own page.
| Degrees Fahrenheit | Degrees Celsius |
|---|---|
| -45 °F | -42.8 °C |
| -44 °F | -42.2 °C |
| -43 °F | -41.7 °C |
| -42 °F | -41.1 °C |
| -41 °F | -40.6 °C |
| -40 °F | -40 °C |
| -39 °F | -39.4 °C |
| -38 °F | -38.9 °C |
| -37 °F | -38.3 °C |
| -36 °F | -37.8 °C |
| -35 °F | -37.2 °C |
How to convert Fahrenheit to Celsius
The formula
°C = (°F − 32) × 5/9. The two scales start from different zero points, so there is a subtraction as well as a multiplication.
Worked through for -40
Subtract 32: -40 − 32 = -72. Multiply by 5/9: -72 × 5 ÷ 9 = -40. Rounded, that is -40 °C.
In your head
Take away 30 and halve it: 70 °F → 40 ÷ 2 = 20 °C (close enough for weather).
Questions
What is -40 °F in Celsius?
-40 degrees Fahrenheit is -40 degrees Celsius, or -40 °C rounded to one decimal place.
How do you convert degrees Fahrenheit to degrees Celsius?
Use (-40 − 32) × 5/9, which gives -40. For a quick estimate: Take away 30 and halve it: 70 °F → 40 ÷ 2 = 20 °C (close enough for weather).
Is -40 °F hot or cold?
-40 °F is -40 °C: bitterly cold, below the temperature of a home freezer.
What is -40 °C in Fahrenheit?
Going the other way, -40 °C is -40 °F. The reverse conversion has its own page and converter.
Is the answer exact?
Yes. -40 °F converts to exactly -40 °C; the rounded figure is only for convenience.