Unit Converters

Millimeters to Inches Converter

Type a value in millimeters to get it in inches, and see the reverse conversion.

By TheCalcTools Updated October 17, 2026 Formula checked and tested

Your numbers

Value in millimeters (mm)

Your results

Converted value

Inches (in)

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1 mm in in

—

Your number read as in, in mm

—

Centimetres (cm)

—

Thousandths of an inch (mil)

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Millimeters to Inches Converter by TheCalcTools

How the Millimeters to Inches Converter works

One inch is exactly 25.4 millimetres. Engineers, machinists and jewellers convert small sizes such as bolt diameters, rain gauges and ring widths this way.

To convert millimeters to inches, multiply by 0.03937007874. The calculator shows the result to 6 significant figures; the conversion factor itself is exact by definition.

Quick estimate in your head: 25 mm is just under 1 inch.

The formula

in = mm × 0.03937007874mm = in ÷ 0.03937007874

Worked example

Using the default values shown in the calculator:

Value in millimeters (mm)	10

10 mm × 0.03937007874 = 0.393701 in.

Result:

Inches (in)	0.393701
1 mm in in	0.0393701
Your number read as in, in mm	254
Centimetres (cm)	1
Thousandths of an inch (mil)	393.701

Conversion table

mm	in
1 mm	0.0393701 in
2 mm	0.0787402 in
3 mm	0.11811 in
5 mm	0.19685 in
6 mm	0.23622 in
8 mm	0.314961 in
10 mm	0.393701 in
12 mm	0.472441 in
15 mm	0.590551 in
20 mm	0.787402 in
25 mm	0.984252 in
50 mm	1.9685 in

Frequently asked questions

What is 1 millimeter in inches?

1 millimeter (mm) equals 0.0393701 in.

Sources and further reading

More in Unit Converters · All calculators

This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.