Engineering DisclaimerEngineering calculations are provided for preliminary design and educational/reference purposes only. Users must verify all results according to applicable engineering standards, supplier data, manufacturing requirements, and professional engineering judgment.
Category: fasteners
Reference Dataset
Metric Fastener Bolt Geometry Dimensions Table
Dimensional envelope sizes for standard ISO metric fasteners including thread pitch, head flats, and height.
Overview & Scope
Metric ISO threads define head widths and socket clearances for assembly tool access. Choosing proper fastener clearances prevents structural interferences during manufacturing.
Technical Sizing Values
The table below specifies thread pitch, head height, and flats clearances parameters for standard metric fasteners.
| Thread Size | Thread Pitch (mm) | Width Across Flats (mm) | Head Height (mm) | Flats Clearances (mm) |
|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 2 | 6.4 |
| M4 | 0.7 | 7 | 2.8 | 8.1 |
| M5 | 0.8 | 8 | 3.5 | 9.2 |
| M6 | 1 | 10 | 4 | 11.5 |
| M8 | 1.25 | 13 | 5.3 | 15 |
| M10 | 1.5 | 16 | 6.4 | 18.4 |
| M12 | 1.75 | 18 | 7.5 | 20.8 |
| M16 | 2 | 24 | 10 | 27.7 |
| M20 | 2.5 | 30 | 12.5 | 34.6 |
Engineering Notes & Best Practices
- •Flats clearances correspond to the socket envelope space required to apply tightening torque.
- •Thread pitch dictates the fine or coarse thread options; coarse threads are the default for general mechanical assemblies.
- •Wrench socket clearances are highly dependent on standardized head shapes.
Dataset Citations & References
ISO 4014 / ISO 4017 Specifications
Public domain source and standard catalog reference parameters.
Machinery's Handbook
Public domain source and standard catalog reference parameters.