What is M10 thread size

M10 thread designation indicates a metric thread with 10 mm nominal major (outer) diameter, using the ISO metric screw thread standard. The complete specification typically includes pitch: M10×1.5 (coarse thread standard, meaning 1.5 mm distance between adjacent thread crests) or M10×1.25 (fine thread variant for applications requiring higher thread strength or finer adjustment). M10 is a medium-size fastener commonly used in automotive, machinery, structural connections, and general engineering applications.

The M10 thread requires specific tap and clearance hole sizes: for M10×1.5 coarse threads, use an 8.5 mm tap drill for threading into materials, or 10.5-11 mm clearance holes for through-bolting. The pitch diameter (critical dimension for thread fit) for M10×1.5 is approximately 9.026-9.206 mm depending on tolerance class (6g typical for bolts, 6H for nuts). M10 fasteners are not directly interchangeable with imperial threads despite some size similarity—3/8"-16 UNC has comparable diameter (9.525 mm) but different thread form and pitch, preventing interchangeability. Common M10 applications include automotive suspension components, industrial machinery mounting, furniture bolts, bicycle components, and structural connections where moderate strength is required. The tensile strength varies by material and grade marking: Grade 8.8 M10 bolts provide substantially higher strength than Grade 4.6, with grade designation indicating minimum tensile and yield strength properties according to ISO 898 standards. When specifying M10 fasteners, include pitch, length, head style, and grade to ensure correct component selection.