For Hex Nuts, Grade C, the M12 thread sits in the medium range of the catalog and is one of the most-asked hex nuts, grade c in this family. The dimensional and assembly data follow.
M12 Dimensional Row (ISO 4034)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m (mm) | Product grade | Reference standard |
|---|---|---|---|---|---|---|
| M12 | 1.75 | 19.0 | 20.88 | 10.8 | Grade C | ISO 4034 / DIN 555 |
Spanner & Drive for M12 Hex Nuts, Grade C
M12 Hex Nuts, Grade C have a width across flats of 19.0 mm — fit a 19.0 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Common Applications for M12 Hex Nuts, Grade C
M12 Hex Nuts, Grade C are commonly specified for medium-duty structural joints and motor / chassis mounting.
Installation Tips for M12 Hex Nuts, Grade C
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
Mating Parts for M12
Pair M12 with the matching M12 bolt or screw, plus a M12 flat washer where required to distribute load on softer materials.
When to Step Up or Down from M12
When the joint preload approaches the proof load of M12 class 8.8, step up to M16 class 8.8 (or move to M12 class 10.9). When the joint is over-specified, M10 often saves weight and cost without losing the safety margin.