Metric Bolt
This metric bolt size chart is based on globally applicable ISO standards and compiled manufacturer datasheets. Each size includes three reference diagrams and a complete dimensions chart covering major and minor diameters, pitch diameter, thread pitch, head dimensions, tap drill size, and clearance hole diameter, with a built-in metric-to-inches converter for users from the United States.
| Size | Last Updated |
|---|---|
| M1 | 2026-02-01 |
| M1.2 | 2026-02-01 |
| M1.4 | 2026-02-01 |
| M1.6 | 2026-02-01 |
| M1.7 | 2026-02-01 |
| M2 | 2026-02-01 |
| M2.3 | 2026-02-01 |
| M2.5 | 2026-02-01 |
| M2.6 | 2026-02-01 |
| M3 | 2026-02-01 |
| M3.5 | 2026-02-01 |
| M4 | 2026-02-01 |
| M5 | 2026-02-01 |
| M6 | 2026-02-11 |
| M7 | 2026-02-01 |
| M8 | 2026-02-01 |
| M10 | 2026-02-01 |
| M12 | 2026-02-01 |
| M14 | 2026-02-01 |
| M16 | 2026-02-01 |
| M18 | 2026-02-01 |
| M20 | 2026-02-01 |
| M22 | 2026-02-01 |
| M24 | 2026-02-01 |
| M27 | 2026-02-01 |
| M30 | 2026-02-01 |
| M33 | 2026-02-01 |
| M36 | 2026-02-01 |
| M39 | 2026-02-01 |
| M42 | 2026-02-01 |
| M45 | 2026-02-01 |
| M48 | 2026-02-01 |
| M52 | 2026-02-01 |
| M56 | 2026-02-01 |
| M60 | 2026-02-01 |
| M64 | 2026-02-01 |
How Metric Bolt Sizes Work
Metric bolts are designated by the letter M followed by a number. The number represents the nominal major thread diameter in millimeters. For example, an M8 bolt has an 8 mm major diameter.
ISO Standards
All sizes listed follow ISO metric fastener standards, which define dimensional tolerances, thread geometry, and mechanical compatibility across manufacturers.