This chart represents the true mathematical equivalent values between inch fractions, decimals and millimeters (mm). It is not to be confused with our socket size conversion chart which gives approximate values between metric and standard sockets (tools).

Fraction Decimal Millimeter
1/64 0.0156 0.396
1/32 0.0312 0.793
3/64 0.0469 1.19
1/16 0.0625 1.587
5/64 0.0781 1.984
3/32 0.0937 2.381
7/64 0.1094 2.778
1/8 0.125 3.175
9/64 0.1406 3.571
5/32 0.1562 .3.968
11/64 0.1719 4.365
3/16 0.1875 4.762
13/64 0.2031 5.159
7/32 0.2187 5.556
15/64 0.2344 5.953
1/4 0.25 6.35
17/64 0.2656 6.746
9/32 0.2812 7.143
19/64 0.2969 7.54
5/16 0.3125 7.937
21/64 0.3281 8.334
11/32 0.3437 8.731
23/64 0.3594 9.129
3/8 0.375 9.525
25/64 0.3906 9.921
13/32 0.4062 10.318
27/64 0.4219 10.715
7/16 0.4375 11.112
29/64 0.4531 11.509
15/32 0.4687 11.906
31/64 0.4844 12.303
1/2 0.5 12.7
33/64 0.5156 13.096
17/32 0.5312 13.493
35/64 0.5469 13.89
9/16 0.5625 14.287
37/64 0.5781 14.684
19/32 0.5937 15.081
39/64 0.6094 15.478
5/8 0.625 15.875
41/64 0.6406 16.271
21/32 0.6562 16.668
43/64 0.6719 17.065
11/16 0.6875 17.462
45/64 0.7031 17.859
23/32 0.7187 18.256
47/64 0.7344 18.653
3/4 0.75 19.05
49/64 0.7656 19.446
25/32 0.7812 19.843
51/64 0.7969 20.24
13/16 0.8125 20.637
53/64 0.8281 21.034
27/32 0.8437 21.431
55/64 0.8594 21.828
7/8 0.875 22.225
57/64 0.8906 22.621
29/32 0.9062 23.017
59/64 0.9219 23.416
15/16 0.9375 23.813
61/64 0.9531 24.209
31/32 0.9687 24.605
63/64 0.984 25.003
1 1 25.4
1 1/4 1.25 31.75
1 1/2 1.5 38.1
1 3/4 1.75 44.45
2 2 50.8
2 1/2 2.5 63.5
3 3 76.2
3 1/2 3.5 88.9
4 4 101.6
4.5 4 1/2 114.3
5 5 127

Inch in MM Conversion Chart Definitions

Inch (in): The inch is a unit of length in the imperial / U.S. measurement systems. It is equivalent to 1/12th of a foot or 25.4 millimeters.

Millimeter (mm): The millimeter is a unit of length in the metric system, where one millimeter is equal to 0.03937 inches.

Conversion Formula

To convert inches to millimeters, use this conversion factor: 1 inch = 25.4 millimeters.

Example: If you have a length of 4 inches and want to convert it to millimeters, the calculation is: Millimeters = 4 x 25.4 = 101.6 (millimeters)

Reverse Conversion

To convert millimeters to inches, use this conversion factor: 1 millimeter = 0.03937 inches.

Example: If you have a length of 50 millimeters and want to convert it to inches, the calculation is: 50 x 0.03937 = 1.9685 (inches rounded).