-40°C to Fahrenheit

-40°F

-40°C = -40°F = 233.15 K

Working: (-40 × 9/5) + 32 = -40

-40 degrees Celsius converts to -40 degrees Fahrenheit.

To convert Celsius to Fahrenheit, multiply by 9/5 (which is 1.8) and then add 32. For -40°C: -40 × 1.8 = -72, and -72 + 32 = -40. Going the other way, subtract 32 from the Fahrenheit value and multiply by 5/9.

If you only need a rough figure, double the Celsius number and add 30 — that gives -50°F here, which is 10 degrees off the exact -40°F. The shortcut is accurate enough for weather but not for cooking or medical use.

Minus forty is the one temperature where the two scales meet: −40°C and −40°F are the same physical temperature, the single point at which the conversion needs no arithmetic. It is also the standard rating point for winter-grade fuels, lubricants, and equipment, which is why it appears on specification sheets far more often than the weather justifies.

Nearby temperatures

Celsius	Fahrenheit
-20°C	-4°F
-10°C	14°F
0°C	32°F
5°C	41°F
10°C	50°F
15°C	59°F
20°C	68°F
25°C	77°F

Try another value

From

°C

77°F

All scales

Celsius (°C)25 °C

Fahrenheit (°F)77 °F

Kelvin (K)298.15 K

Frequently asked questions

What is -40 degrees Celsius in Fahrenheit?

-40°C is -40°F. Multiply -40 by 1.8 to get -72, then add 32 to get -40.

What is the formula for Celsius to Fahrenheit?

°F = (°C × 9/5) + 32. Multiply the Celsius temperature by 1.8, then add 32. To reverse it, subtract 32 first and then multiply by 5/9.

For any other value, use the full Temperature Converter on BrainVert.