M8×125

M8×125 is a designation used for metric fasteners, typically bolts. The M8 part indicates a nominal thread diameter of 8 millimeters, while the 125 denotes a length of 125 millimeters. It is commonly encountered in machinery, automotive, and construction applications where longer fasteners are required.

The standard thread pitch for an M8 coarse thread is 1.25 millimeters. Fine-pitch variants exist, such as M8×1.0, but M8×125 generally refers to a long bolt with the standard pitch if not otherwise stated. The actual threaded portion length depends on the specific part; some bolts are partially threaded, while others are fully threaded to the full length.

These fasteners are manufactured to ISO metric standards and come in various head types, including hex bolts (ISO 4017), socket-cap screws (ISO 4762), and other styles. Common material grades include steel such as 8.8, 10.9, or stainless steel, with coatings like zinc plating, black oxide, or passivation to suit environmental conditions.

Usage and selection considerations include ensuring sufficient thread engagement for the joint and selecting an appropriate length to achieve the required clamping along with the proper head type for tool access. Torque values depend on diameter, material, thread pitch, and coating, so they should be determined from applicable standards or manufacturer specifications. Because 125 mm is a relatively long length, these bolts are chosen for assemblies requiring deep engagement or through-bolting.

Availability and equivalents: M8×125 bolts are widely offered by fastener suppliers in multiple materials, finishes, and head styles. When sourcing, it is important to verify exact specifications—diameter, length, thread pitch, head type, material, and grade—to ensure proper fit and performance.