Millimetres to Inches
Divide by 25.4, exactly.
Millimetres are the working unit of engineering drawings, fastener specifications and camera lenses, so this conversion tends to come up when reading a spec written in one system while holding a tool marked in the other.
Watch out for one thing: a 6mm bolt and a ¼in bolt are close (6mm is 0.236in) and are not interchangeable. Near enough is not a tolerance.
The formula
inches = millimetres ÷ 25.4
Millimetres to Inches table
| Millimetres | Inches |
|---|---|
| 1 | 0.0393700787 |
| 5 | 0.196850394 |
| 10 | 0.393700787 |
| 12.7 | 0.5 |
| 25.4 | 1 |
| 50 | 1.96850394 |
| 100 | 3.93700787 |
| 200 | 7.87401575 |
| 500 | 19.6850394 |