Overview
This table lists the standard nominal diameter, coarse thread pitch, and wrench (spanner) size for metric bolts per ISO 261 and ISO 898-1. Values are for coarse-thread series unless noted.
Standard Table
| Nominal Diameter | Coarse Pitch (mm) | Fine Pitch (mm) | Wrench Size (mm) | Head Height (mm) |
|---|---|---|---|---|
| M3 | 0.50 | — | 5.5 | 2.0 |
| M4 | 0.70 | — | 7.0 | 2.8 |
| M5 | 0.80 | — | 8.0 | 3.5 |
| M6 | 1.00 | 0.75 | 10.0 | 4.0 |
| M8 | 1.25 | 1.00 | 13.0 | 5.3 |
| M10 | 1.50 | 1.25 | 16.0 | 6.4 |
| M12 | 1.75 | 1.25 | 18.0 | 7.5 |
| M14 | 2.00 | 1.50 | 21.0 | 8.8 |
| M16 | 2.00 | 1.50 | 24.0 | 10.0 |
| M20 | 2.50 | 1.50 | 30.0 | 12.5 |
| M24 | 3.00 | 2.00 | 36.0 | 15.0 |
| M30 | 3.50 | 2.00 | 46.0 | 18.7 |
| M36 | 4.00 | 3.00 | 55.0 | 22.5 |
| M42 | 4.50 | 3.00 | 65.0 | 26.0 |
| M48 | 5.00 | 3.00 | 75.0 | 30.0 |
| M56 | 5.50 | 4.00 | 85.0 | 35.0 |
| M64 | 6.00 | 4.00 | 95.0 | 40.0 |
Notes
- Coarse pitch is the standard thread series for general applications.
- Fine pitch threads are used where vibration resistance or thin-walled sections are required.
- Wrench sizes conform to ISO 272 (hexagon bolts and nuts).
- Property classes per ISO 898-1: 4.6, 5.8, 8.8, 10.9, 12.9.
References
- ISO 261:1998 — ISO general purpose metric screw threads — General plan
- ISO 898-1:2013 — Mechanical properties of fasteners made of carbon steel and alloy steel
- ISO 272:1982 — Fasteners — Hexagon products — Widths across flats