Multiply mm by 0.0393700787 to get in. The displayed factor is rounded; the calculator uses the full stored conversion factor.
One inch is exactly 25.4 mm. The result is decimal inches, useful for comparing metric dimensions with inch specifications.
Worked example
25.4 mm = 1 in. To reverse it, enter the unrounded output and select Swap units. Round only the final result; converting an already-rounded result back may not reproduce the original exactly.
Conversion table in both directions
mm and in reference values
Input
mm → in
in → mm
1
0.0393700787
25.4
2
0.0787401575
50.8
5
0.1968503937
127
10
0.3937007874
254
20
0.7874015748
508
25
0.9842519685
635
50
1.968503937
1,270
100
3.937007874
2,540
500
19.6850393701
12,700
1000
39.3700787402
25,400
Last updated . Results are estimates for informational purposes only.