How to convert inches to millimeters
- Type the value in inches (in) in the box above.
- The result in millimeters appears instantly, along with the same value in every other unit of length.
- Press ⇄ to convert the other way.
Formula
millimeters = inches × 25.4. So 1 in = 25.4 mm, and 0.5 in = 12.7 mm.
Inches to millimetres is common when replacing imperial fasteners or pipe fittings with metric ones, converting plans for a 3D printer or CNC machine, and comparing tool sizes. Multiply by exactly 25.4. The table includes the usual fractions: 1/16, 1/8, 1/4, 3/8, 1/2 and 3/4 of an inch.
in to mm conversion chart
| Inches | Millimeters |
|---|---|
| 0.0625 in | 1.5875 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 |
| 0.75 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 |
| 6 in | 152.4 mm |
FAQ
How many mm is 1/2 inch?
Exactly 12.7 mm.
How do I convert in to mm?
Use millimeters = inches × 25.4. Or type the value above and the converter does it for you.
How do I convert mm back to in?
Multiply by 0.03937, or press the ⇄ button in the converter.