Millimeters to inches

1 millimeter = 0.0393701 inches

Type a value in millimeters (mm) to get inches (in) straight away. A millimeter is smaller than an inch, so the number goes down. Both units belong to length, measured here against the meter.

FromTo0.039370079

1 mm = 0.039370079 in

Formula

in = mm × 0.039370079

One millimeter is 0.039370079 inches, so multiply by that factor. You can also divide by 25.4, the number of millimeters in one inch. Here mm is the value in millimeters and in is the result in inches.

Worked example: 250 millimeters × 0.039370079 = 9.84252 inches.

Millimeters to inches table

millimeters (mm)	inches (in)
1 mm	0.0393701 in
2 mm	0.0787402 in
3 mm	0.11811 in
4 mm	0.15748 in
5 mm	0.19685 in
6 mm	0.23622 in
7 mm	0.275591 in
8 mm	0.314961 in
9 mm	0.354331 in
10 mm	0.393701 in
15 mm	0.590551 in
20 mm	0.787402 in
25 mm	0.984252 in
30 mm	1.1811 in
40 mm	1.5748 in
50 mm	1.9685 in
60 mm	2.3622 in
75 mm	2.95276 in
100 mm	3.93701 in

Everyday millimeters in inches

What it is	mm	in
a sheet of paper (about)	0.1 mm	0.00393701 in
a standard pencil lead	2 mm	0.0787402 in
a 8 mm drill bit	8 mm	0.314961 in
the short side of an A4 sheet	210 mm	8.26772 in
the long side of an A4 sheet	297 mm	11.6929 in

Quick estimate in your head

Multiply by about 0.039. For 250 mm that gives 9.75 in against an exact 9.84252 in, an error of 0.9%.

About the units

Millimeter (mm). One thousandth of a meter. Used for engineering drawings, rainfall and screen sizes in some countries.

Inch (in). Exactly 2.54 cm since the 1959 international yard agreement. Common for screens, tyres and pipes.

Going the other way, 1 inch is 25.4 millimeters.

Questions

How many inches are in 1 millimeter?

1 millimeter is 0.0393701 inches, and 1 inch is 25.4 millimeters.

How do I convert millimeters to inches?

Use in = mm × 0.039370079. For example, 250 millimeters × 0.039370079 = 9.84252 inches.

Is the millimeter to inch factor exact?

The factor comes from the unit definitions. Results here are rounded to 6 significant digits for display.

How much is the long side of an A4 sheet in inches?

297 mm is 11.6929 in.

Source for the conversion factor: NIST SP 811, Appendix B (conversion factors).

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