-40 Celsius to Fahrenheit

-40°C = -40°F

-40 degrees Celsius is equal to -40 degrees Fahrenheit.

Convert -40 Celsius to Fahrenheit using our free temperature converter.

How to convert -40 °C to °F

Use the formula °F = (°C × 9/5) + 32 and substitute -40 for °C:

°F = (-40 × 9/5) + 32
°F = -72 + 32
°F = -40

So -40 °C = -40 °F.

What does -40 °C mean?

This is the one temperature where the Celsius and Fahrenheit scales meet: −40 °C is exactly −40 °F. It is a handy way to remember that the two scales are not simply offset from each other.

-40 °C is very cold weather, well below the freezing point of water. It is typical of a hard winter in northern climates; warm layers, gloves and a hat are essential outdoors.

Fahrenheit: -40 °F
Kelvin: 233.15 K
Quick estimate (double + 30): -50 °F

For -40 °C the quick “double it and add 30” estimate gives -50 °F — 10 °F too low. The shortcut works best between about 0 °C and 20 °C; use the exact formula for anything that matters.

-40 °C and nearby values

Celsius to Fahrenheit near -40 °C
Celsius	Fahrenheit
-44 °C	-47.2 °F
-43 °C	-45.4 °F
-42 °C	-43.6 °F
-41 °C	-41.8 °F
-40 °C	-40 °F
-39 °C	-38.2 °F
-38 °C	-36.4 °F
-37 °C	-34.6 °F
-36 °C	-32.8 °F

The Celsius to Fahrenheit formula

°F = (°C × 9/5) + 32

Multiply the Celsius temperature by 9/5 (1.8) because a Celsius degree is 1.8 times larger than a Fahrenheit degree, then add 32 because water freezes at 32 °F rather than 0 °F. To go the other way, use °C = (°F − 32) × 5/9 — for example, -40 °F back to Celsius gives -40 °C.

See the formula explained in detail or the step-by-step conversion guide.

Frequently asked questions

What is -40 Celsius in Fahrenheit?

-40 degrees Celsius is equal to -40 degrees Fahrenheit (-40 °C = -40 °F).

How do you convert -40 °C to °F?

Multiply -40 by 9/5 (or 1.8) and add 32: (-40 × 1.8) + 32 = -40 °F.

Is -40 °C hot or cold?

It is very cold — well below freezing. -40 °C is -40 °F.

What is -40 °C in Kelvin?

Add 273.15 to the Celsius value: -40 °C = 233.15 K.