M8 Bolts

An M8 bolt is a metric fastener with a nominal 8 mm thread major diameter. “M8” describes the diameter, and the full thread callout typically also includes the thread pitch, such as M8 × 1.25 (the most common “coarse” pitch) or M8 × 1.0 (a finer pitch). M8 bolts are widely used in automotive, machinery, equipment frames, furniture, and general industrial assemblies because they offer a versatile balance of size, strength, and availability.

When selecting an M8 bolt, it’s important to match the pitch and choose the right property class (such as 8.8, 10.9, or 12.9) and material/finish for the environment. Even though two bolts may both be M8, they will not assemble with the same nut or tapped hole unless the pitch matches. Length is measured from under the head for most head styles, and the correct bolt length depends on joint thickness, washers, and required thread engagement.