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Metric Bolt Torque


In auto repair and replacement, fasteners are often replaced as well as the parts they connect. For this reason, it's important to use both the correct bolts and nuts to match when replacing - not just the right size. Identifying grade marks on metrics is easy - the grade is literally stamped onto the head (e.g. "8.8" or "12.9"). On hex-head bolts, it will be on the flat surface of the head, on others it may be on the side or even underneath.

The following is a torque chart of common metric sizes, thread pitches, and grades showing their recommended maximum torque in ft-pounds. Manufacturer-recommended torque settings will trump these, of course. The following assumes unfinished, non-lubricated products. For SAE bolt torque values, click here.

Size Thread pitch Low grade 8.8 grade 10.9 grade 12.9 grade
M6 1.0 3-5 7 10 12
M8 1.25 8-12 17 24 29
M10 1.5 15-22 37 53 62
M12 1.75 39 65 93 108
M14 2.0 - 104 148 173
M16 2.0 - 161 230 269
M18 2.5 - 222 318 372
M20 2.5 - 314 449 525
M22 2.5 - 428 613 716
M24 3.0 - 543 776 908

As with SAE bolts, remember that torque ratings are for tensile strength, not sheer. So the strength of the bolt is measured parallel to its shaft (i.e. it's "pulling" value) and not perpendicular (sheer). In fact, the heavier the grade, the higher the carbon value of the metals used and the more brittle they are in terms of sheer.

Because engineers keep this in mind while designing applications, be sure you're using the same (no more, no less) grade of bolt the application calls for.

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Metric Bolt Torque Specs