# How many millimeters are in one inch?

**By definition there are exactly 25.4 millimeters per
inch.**

**Effective July 1, 1959**, the United States and countries
of the British Commonwealth defined the length of the international
yard to be exactly 0.9144 meters. Consequently, the international
inch is defined to be equal to exactly 25.4 millimeters.

To convert millimeters into inches, divide millimeters by 25.4.

To convert inches into millimeters, multiply inches by
25.4.

25.4 millimeters ==

25,4 mm

25.4 mm = 1 inch

Algebraic Steps / Dimensional Analysis Formula1 in*

2.54 cm

1 in

*

10 mm

1 cm

=

25.4 mm

There are 25.4 millimeters in 1 inch.

But, if you are measuring Millers, I'd say the average male
miller is .01388889 Millers per inch, or 72 inches per
Miller.

There are 25.4 millimetres in one inch.