The M12 size of Hex Nuts is dimensioned by ISO 4032 / ISO 4033. The tables below give the dimensional row from the standard, the drill and spanner sizes that go with it, and the assembly torque per property class. The technical drawing on this page redraws to the exact values selected.
M12 Dimensional Row (ISO 4032 / ISO 4033)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m style 1 (mm) | Nut height m style 2 (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M12 | 1.75 | 18.0 | 20.03 | 10.0 | 12.0 | ISO 4032 (Style1) / ISO 4033 (Style2) |
Spanner & Drive for M12 Hex Nuts
M12 Hex Nuts have a width across flats of 18.0 mm — fit a 18.0 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
M12 Hex Nuts are commonly specified for medium-duty structural joints and motor / chassis mounting.
Installation Tips for M12 Hex Nuts
- 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.
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.