Inches to MM Converter
Convert inches to millimeters (in to mm) instantly, with the formula and a conversion chart.
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How to convert inches to millimeters
1 inch = 25.4 millimeters. To convert inches to millimeters, multiply by 25.4.
Example: 0.5 in = 12.7 mm.
Handy for converting imperial wrench, bolt and pipe sizes — 1/4", 1/2", 3/4" — to their metric equivalents.
Inches to MM conversion chart
| Inches | Millimeters |
|---|---|
| 0.0625 in | 1.588 mm |
| 0.125 in | 3.175 mm |
| 0.25 in | 6.35 mm |
| 0.375 in | 9.525 mm |
| 0.5 in | 12.7 mm |
| 0.625 in | 15.875 mm |
| 0.75 in | 19.05 mm |
| 1 in | 25.4 mm |
| 1.5 in | 38.1 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
How to use this tool
- 1Type the number of inches in the Value box.
- 2The result in millimeters appears instantly.
- 3Use the ⇄ button to convert millimeters to inches instead, or pick any other unit.
Features
- Exact in to mm conversion using the standard definition.
- Results update as you type, rounded to 6 decimal places.
- Switch to any other length, weight, temperature, volume or speed unit.
Privacy
Everything is calculated in your browser. Nothing is sent to a server.
Frequently asked questions
How many mm is 1/4 inch?
1/4 inch (0.25 in) is 6.35 mm.
How many mm is 1/2 inch?
1/2 inch is 12.7 mm.
How do I convert millimeters back to inches?
Divide by 25.4 (or multiply by 0.0393701), or use the swap button in the converter above or the MM to Inches converter.
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