Inches to Millimeters

Convert in to mm instantly — with a table, common fractions, and a live calculator.

1 in equals 25.4 mm.

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Result (mm)25.4 mm

in to mm table

inmm
0.25 in6.35 mm
0.5 in12.7 mm
0.75 in19.05 mm
1 in25.4 mm
1.5 in38.1 mm
2 in50.8 mm
2.5 in63.5 mm
3 in76.2 mm
4 in101.6 mm
5 in127 mm
6 in152.4 mm
8 in203.2 mm
10 in254 mm
12 in304.8 mm
14.5 in368.3 mm
15 in381 mm
16 in406.4 mm
20 in508 mm
24 in609.6 mm
36 in914.4 mm
50 in1270 mm
100 in2540 mm

mm to in (reverse)

mmin
0.25 mm0.00984 in
0.5 mm0.0197 in
0.75 mm0.0295 in
1 mm0.0394 in
1.5 mm0.0591 in
2 mm0.0787 in
2.5 mm0.0984 in
3 mm0.118 in
4 mm0.157 in
5 mm0.197 in
6 mm0.236 in
8 mm0.315 in
10 mm0.394 in
12 mm0.472 in
14.5 mm0.571 in
15 mm0.591 in
16 mm0.63 in
20 mm0.787 in
24 mm0.945 in
36 mm1.42 in
50 mm1.97 in
100 mm3.94 in

Common fractions

inmm
1/16 in1.59 mm
1/8 in3.18 mm
3/16 in4.76 mm
1/4 in6.35 mm
3/8 in9.53 mm
1/2 in12.7 mm
5/8 in15.88 mm
3/4 in19.05 mm
1 in25.4 mm
1 1/4 in31.75 mm
1 1/2 in38.1 mm
2 in50.8 mm

How it scales

25517610201234in

1 meter in other units

1000mm100cm39.4in3.3ft1.1yd

The ratio at a glance

1 in25.4 mm

Imperial and metric units

Inches, feet, yards, and miles belong to the imperial/US system, while millimeters, centimeters, meters, and kilometers are metric. One international inch is defined as exactly 25.4 mm.

Length-to-length conversions are exact and rest on fixed factors — for more unit pairs, use our length conversion hub.

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Frequently asked questions

How many mm are in a in?

1 in equals 25.4 mm.

How many mm are in 2 in?

2 in equal 50.8 mm.

How do I convert in to mm?

Multiply the number of in by 25.4 to get mm.

How is an inch defined?

One international inch is defined as exactly 25.4 millimeters. This definition is used worldwide, so the conversions on this page are exact.

Why are there imperial and metric units?

Inches, feet, yards, and miles belong to the imperial/US system, while millimeters, centimeters, meters, and kilometers are metric. All conversions rest on fixed, exact factors.

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