Metric Threads
14 indexed entriesPart of Tools & Home Improvement.
Items
M1.6
M1.6 is one of the smallest ISO metric bolt sizes in regular production, with a 1.6mm major diameter and 0.35mm thread pitch. Tap drill size is 1.25mm. Typical Class 8.8 tightening torque is just 0.18 Nm -- light enough that these fasteners are almost always hand-tightened rather than torque-wrenched.
M10
An M10 bolt features a 10.0mm major diameter and a 1.50mm coarse pitch. Tap drill size is 8.5mm with a 17mm or 16mm hex wrench. Torque for Class 8.8 is 49.0 Nm.
M12
An M12 bolt features a 12.0mm major diameter and a 1.75mm coarse pitch. Tap drill bit size is 10.2mm. Standard tightening torque for Class 8.8 steel is 85.0 Nm.
M14
M14 has a 14mm major diameter, 2.0mm coarse pitch (1.5mm fine option), and a 12mm tap drill. Recommended tightening torque is about 135 Nm for Class 8.8 and 190 Nm for Class 10.9. Hex head wrench size differs by standard: 22mm under older DIN 931/933, 21mm under current ISO 4014/4017.
M16
An M16 bolt features a 16.0mm major diameter and a 2.00mm coarse pitch. Tap drill bit size is 14.0mm with a 24mm hex head wrench. Tightening torque for Class 8.8 is 210.0 Nm.
M2
An M2 metric bolt features a 2.0mm major diameter and a standard coarse pitch of 0.40mm. The recommended tap drill size is 1.6mm with a 4.0mm hex socket driver.
M2.5
M2.5 falls between M2 and M3 in the ISO metric range, with a 2.5mm major diameter and 0.45mm coarse pitch. Its 2.05mm tap drill and 5mm hex wrench make it a common size in laptop and small-appliance assembly, camera hardware, and compact electronics enclosures.
M20
M20 has a 20mm major diameter, 2.5mm coarse pitch (2.0 or 1.5mm fine options), and a 17.5mm tap drill. Recommended tightening torque runs about 410 Nm for Class 8.8 and 580 Nm for Class 10.9 -- high enough that a torque wrench or breaker bar is required rather than hand tightening.
M24
M24 has a 24mm major diameter, 3.0mm coarse pitch (2.0mm fine option), and a 21mm tap drill. Recommended tightening torque is roughly 690 Nm for Class 8.8 and 970 Nm for Class 10.9 -- torque levels that require hydraulic or pneumatic tooling rather than a hand wrench.
M3
An M3 bolt has a 3.0mm major diameter and a standard 0.50mm coarse thread pitch. The required tap drill size is 2.5mm. Standard tightening torque for Class 8.8 steel is 1.3 Nm.
M4
An M4 bolt features a 4.0mm major diameter and a 0.70mm coarse thread pitch. The required tap drill bit size is 3.3mm with a standard tightening torque of 3.0 Nm for Class 8.8 steel.
M5
An M5 bolt has a 5.0mm major diameter and an 0.80mm thread pitch. Tap drill bit size is 4.2mm. Standard torque rating for Class 8.8 steel is 6.0 Nm.
M6
An M6 bolt features a 6.0mm major diameter and a 1.00mm thread pitch. The required tap drill size is 5.0mm with a standard hex wrench size of 10.0mm. Recommended torque is 10.0 Nm for Class 8.8 steel.
M8
A standard coarse M8 bolt has an 8.0mm major diameter and a 1.25mm thread pitch. The required tap drill size is 6.8mm (or an F letter drill in imperial). Standard tightening torque for Class 8.8 steel is 25 Nm (18.5 lb-ft).