-40 Celsius to Fahrenheit
-40 degrees Celsius equals
-40°F
-40 degrees Fahrenheit
-40°C is -40°F — deep-freeze territory, colder than a household freezer and cold enough to risk frostbite on exposed skin within minutes. -40°C is the single point where both scales agree, reading -40°F as well.
How to convert -40°C to °F
Formula
°F = °C × 9/5 + 32
Substituting -40°C
- -40 × 9/5 = -72
- -72 + 32 = -40
The two scales differ in both their zero point and their step size. A Fahrenheit degree is 5/9 the size of a Celsius degree, and the scales are offset by 32 degrees at the freezing point of water — which is why the conversion needs both a multiplication and an addition.
How -40°C compares
| Reference point | Temperature | Difference |
|---|---|---|
| Freezing point of water | 0°C / 32°F | 40°C (72°F) colder |
| Room temperature | 21°C / 69.8°F | 61°C (109.8°F) colder |
| Body temperature | 37°C / 98.6°F | 77°C (138.6°F) colder |
| Boiling point of water | 100°C / 212°F | 140°C (252°F) colder |