Length conversion

Millimetres to Inches (mm to in)

Q: How many inches are in one millimetre?

One millimetre equals 0.0394 in. To convert any amount, multiply the number of millimetres by 0.0394.

Q: What is 5 mm in in?

5 mm = 0.1968 in. Type any value into the converter above to get an exact answer.

1 mm = 0.0394 in — multiply the number of millimetres by 0.0394.

millimetres

inches

All units & categories

Millimetres to Inches conversion chart

millimetres	inches
1 mm	0.0394 in
2 mm	0.0787 in
3 mm	0.1181 in
4 mm	0.1575 in
5 mm	0.1968 in
6 mm	0.2362 in
7 mm	0.2756 in
8 mm	0.315 in
9 mm	0.3543 in
10 mm	0.3937 in
12 mm	0.4724 in
15 mm	0.5906 in
18 mm	0.7087 in
20 mm	0.7874 in
25 mm	0.9843 in
30 mm	1.1811 in
40 mm	1.5748 in
50 mm	1.9685 in
60 mm	2.3622 in
75 mm	2.9528 in
100 mm	3.937 in

How to convert by hand

1 mm = 0.0393700787 in

Because this is a linear conversion, the ratio never changes: every millimetre is always 0.0394 in, whatever the size of the number.

Worked example: 10 mm × 0.0394 = 0.3937 in .

Related conversions

About millimetres and inches

Length conversions come up constantly when a product is specified in one system and you think in the other — screen sizes in inches, running distances in kilometres, height in feet.

Millimetre

Metric (SI)

One thousandth of a metre.

Commonly used for: Engineering drawings, rainfall totals and material thicknesses.

Inch

US / Imperial

Defined as exactly 2.54 centimetres since the 1959 international yard agreement.

Commonly used for: Screen sizes, tyre diameters and US construction.

Questions

How many inches are in one millimetre?

One millimetre equals 0.0394 in. To convert any amount, multiply the number of millimetres by 0.0394.

What is 5 mm in in?

5 mm = 0.1968 in. Type any value into the converter above to get an exact answer.

How do I convert inches back to millimetres?

Divide by 0.0394 instead of multiplying — or use our Inches to Millimetres converter.

Is this converter accurate?

Yes. Linear conversions use the internationally agreed factors published by NIST (SP 811), and temperature conversions use the exact defining formulas. Calculations run at full double precision and are only rounded for display.

Need a different unit?

The full converter handles length, mass, volume, area, speed and temperature — with every metric and US/UK unit in one place.

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