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.

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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