Free length calculator
Inches to Millimeters Converter (in to mm)
Enter a value to convert inches to millimeters. Results update as you type and include the calculation steps.
in
Result
Enter a value above
In decimal inches
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As a common fraction
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Feet and inches
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How to convert inches to millimeters
Multiply the inches value by 25.4.
mm = in x 25.4
Worked example
For 20 in: 20 x 25.4 = 508 mm.
The calculator keeps more precision internally than the number displayed, so repeated conversions remain accurate.
Inches to Millimeters conversion table
| Inches (in) | Millimeters (mm) |
|---|---|
| 0.1 in | 2.54 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
| 250 in | 6350 mm |
| 500 in | 12700 mm |
| 1000 in | 25400 mm |
About the units
Inch
An inch is a US customary and imperial length unit. One inch equals exactly 25.4 millimeters and one twelfth of a foot.
Millimeter
A millimeter is one thousandth of a meter, one tenth of a centimeter, and exactly 1/25.4 of an inch.