Engineering Tools
Reference data for specifying and sourcing fasteners correctly — the numbers a procurement or design engineer actually needs.
Imperial ↔ metric conversion
Common fractional inch sizes with decimal inch and millimetre equivalents.
| Fraction | Decimal (in) | Millimetres |
|---|---|---|
| 1/16" | 0.0625" | 1.588 mm |
| 1/8" | 0.125" | 3.175 mm |
| 3/16" | 0.1875" | 4.763 mm |
| 1/4" | 0.25" | 6.35 mm |
| 5/16" | 0.3125" | 7.938 mm |
| 3/8" | 0.375" | 9.525 mm |
| 7/16" | 0.4375" | 11.113 mm |
| 1/2" | 0.5" | 12.7 mm |
| 9/16" | 0.5625" | 14.288 mm |
| 5/8" | 0.625" | 15.875 mm |
| 3/4" | 0.75" | 19.05 mm |
| 7/8" | 0.875" | 22.225 mm |
| 1" | 1.0" | 25.4 mm |