40°F to Celsius

4.4°C

40°F = 4.4°C = 277.59 K

Working: (40 − 32) × 5/9 = 4.4

40 degrees Fahrenheit converts to 4.4 degrees Celsius.

To convert Fahrenheit to Celsius, subtract 32 first, then multiply by 5/9. For 40°F: 40 − 32 = 8, and 8 × 5/9 = 4.4. The subtraction comes first because the two scales have different zero points — water freezes at 0°C but at 32°F.

A quick mental estimate is to subtract 30 and halve the result, which gives about 5°C — 0.6 degrees off the exact 4.4°C. That is close enough to judge the weather, though it drifts badly at oven temperatures.

Forty degrees is the temperature American food safety guidance is written around: refrigerators are to be kept at or below 40°F. In metric countries the equivalent rule is written as 5°C, which is 41°F — close enough that the two standards are treated as the same rule despite not being the same number.

Nearby temperatures

Fahrenheit	Celsius
0°F	-17.8°C
32°F	0°C
50°F	10°C
60°F	15.6°C
68°F	20°C
72°F	22.2°C
80°F	26.7°C
90°F	32.2°C

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 Fahrenheit in Celsius?

40°F is 4.4°C. Subtract 32 from 40 to get 8, then multiply by 5/9 to get 4.4.

What is the formula for Fahrenheit to Celsius?

°C = (°F − 32) × 5/9. Subtract 32 from the Fahrenheit temperature, then multiply the result by 5/9 (about 0.5556).

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