Fahrenheit to Celsius

Subtract 32, then multiply by 5/9. Taking thirty off and halving is the mental version — 70°F gives 20 against a true 21.1.

The rows include the numbers that carry meaning rather than round ones: 98.6°F is the traditional figure for body temperature, though it comes from a 19th-century average and modern studies put the norm slightly lower and quite variable. 100.4°F, or 38°C, is the threshold most clinical guidance uses for a fever.

And −40°F is −40°C, the one point where the scales meet.

The formula

°C = (°F − 32) × 5/9

Fahrenheit to Celsius table

Fahrenheit	Celsius
-40	-40
0	-17.7777778
32	0
50	10
68	20
98.6	37
100.4	38
212	100
350	176.666667