Inches to millimeters.
One inch equals exactly 25.4 millimeters. The most common conversion for precision engineering and 3D printing.
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All units.
Conversion formula.
1 in = 25.4 mm
To convert inch to millimeter, multiply the value in in by 25.4.
Quick examples
- 1 in = 25.4 mm
- 5 in = 127 mm
- 10 in = 254 mm
- 100 in = 2540 mm
Inch to Millimeter conversion table.
| Inch (in) | Millimeter (mm) |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 4 | 101.6 |
| 5 | 127 |
| 6 | 152.4 |
| 7 | 177.8 |
| 8 | 203.2 |
| 9 | 228.6 |
| 10 | 254 |
| 11 | 279.4 |
| 12 | 304.8 |
| 13 | 330.2 |
| 14 | 355.6 |
| 15 | 381 |
| 16 | 406.4 |
| 17 | 431.8 |
| 18 | 457.2 |
| 19 | 482.6 |
| 20 | 508 |
Related conversions.
Frequently asked questions.
How many millimeters are in an inch?
One inch equals exactly 25.4 millimeters.
How do I convert inches to mm?
Multiply inches by 25.4. For example, 2 inches × 25.4 = 50.8 mm.
Why is 1 inch 25.4 mm?
Since 1959, the inch has been internationally defined as exactly 25.4 millimeters.