EngiRef / Metric Bolt Specification
M8
M8 coarse-thread metric bolt: 1.25 mm pitch, 8 mm major diameter. Tensile stress area 36.6 mm² per ISO 898-1. Takes a 13 mm wrench. Free bolt specification…
Specification
- Size
- M8
- Pitch (mm)
- 1.25
- Major diameter d (mm)
- 8
- Minor diameter d₃ (mm, external thread)
- 6.47
- Tensile stress area (mm²)
- 36.6
- Head height (mm)
- 5.3
- Head diameter (mm)
- 13
- Wrench size (mm)
- 13
Tensile stress area follows ISO 898-1, At = (π/4)(d − 0.9382p)². Verify against the current standard and the fastener manufacturer's data before safety-critical design.