Inches to Millimeters (in to mm)

mm to inches (Swap Units)
Inches Millimeters
0in 0mm
1in 25.39999983236mm
2in 50.79999966472mm
3in 76.19999949708mm
4in 101.59999932944mm
5in 126.9999991618mm
6in 152.39999899416mm
7in 177.79999882652mm
8in 203.19999865888mm
9in 228.59999849124mm
10in 253.9999983236mm
11in 279.39999815596mm
12in 304.79999798832mm
13in 330.19999782068mm
14in 355.59999765304mm
15in 380.9999974854mm
16in 406.39999731776mm
17in 431.79999715012mm
18in 457.19999698248mm
19in 482.59999681484mm
20in 507.9999966472mm
21in 533.39999647956mm
22in 558.79999631192mm
23in 584.19999614428mm
24in 609.59999597664mm
25in 634.999995809mm
26in 660.39999564136mm
27in 685.79999547372mm
28in 711.19999530608mm
29in 736.59999513844mm
30in 761.9999949708mm
31in 787.39999480316mm
32in 812.79999463552mm
33in 838.19999446788mm
34in 863.59999430024mm
35in 888.9999941326mm
36in 914.39999396496mm
37in 939.79999379732mm
38in 965.19999362968mm
39in 990.59999346204mm
40in 1015.9999932944mm
41in 1041.39999312676mm
42in 1066.79999295912mm
43in 1092.19999279148mm
44in 1117.59999262384mm
45in 1142.9999924562mm
46in 1168.39999228856mm
47in 1193.79999212092mm
48in 1219.19999195328mm
49in 1244.59999178564mm
50in 1269.999991618mm
51in 1295.39999145036mm
52in 1320.79999128272mm
53in 1346.19999111508mm
54in 1371.59999094744mm
55in 1396.9999907798mm
56in 1422.39999061216mm
57in 1447.79999044452mm
58in 1473.19999027688mm
59in 1498.59999010924mm
60in 1523.9999899416mm
61in 1549.39998977396mm
62in 1574.79998960632mm
63in 1600.19998943868mm
64in 1625.59998927104mm
65in 1650.9999891034mm
66in 1676.39998893576mm
67in 1701.79998876812mm
68in 1727.19998860048mm
69in 1752.59998843284mm
70in 1777.9999882652mm
71in 1803.39998809756mm
72in 1828.79998792992mm
73in 1854.19998776228mm
74in 1879.59998759464mm
75in 1904.999987427mm
76in 1930.39998725936mm
77in 1955.79998709172mm
78in 1981.19998692408mm
79in 2006.59998675644mm
80in 2031.9999865888mm
81in 2057.39998642116mm
82in 2082.79998625352mm
83in 2108.19998608588mm
84in 2133.59998591824mm
85in 2158.9999857506mm
86in 2184.39998558296mm
87in 2209.79998541532mm
88in 2235.19998524768mm
89in 2260.59998508004mm
90in 2285.9999849124mm
91in 2311.39998474476mm
92in 2336.79998457712mm
93in 2362.19998440948mm
94in 2387.59998424184mm
95in 2412.9999840742mm
96in 2438.39998390656mm
97in 2463.79998373892mm
98in 2489.19998357128mm
99in 2514.59998340364mm
100in 2539.999983236mm


Use of the inch can be traced back as far as the 7th century. The first explicit definition we could find of its length was after 1066 when it was defined as the length of three barleycorns. This was not a satisfactory reference as barleycorn lengths vary naturally. The British Standards Institute defined the inch as 25.4mm in 1930 in the document "Metric Units in Engineering: Going SI". In March 1932 the American Standards Association were asked to rule on whether to adopt the same value (at the time the American inch was 1/.03937 mm which approximated to 25.400051 mm). Because the values were so close, and because Britain has already settled on that value, the ASA adopted this value on March 13, 1933.

mm =


The millimetre is a unit of length in the metric system, equivalent to one thousandth of a metre (the SI base unit of length).

One meter was defined in 1983 by the 17th conference of weights and measures as “the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second” and the millimetre by definition is derived as being 1/1000th of that value.

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