M8 and M12 look like the same idea at two sizes, and they are. The real question is when the smaller one is enough and when it isn’t. Here’s the comparison that decides it.
Side by side
| M8 | M12 | |
|---|---|---|
| Thread diameter | 8 mm | 12 mm |
| Common poles | 3 / 4 / 6 / 8 | 4 / 5 / 8 / 12 |
| Max current | 4 A | 4 A (16 A L-coded) |
| Ethernet | Rare | D-coded, X-coded |
| IP rating | IP67 | IP67 / IP68 / IP69K |
| Cable OD | 3.5 – 5 mm | 6 – 8 mm |
| Cost | Lower | Higher |
Choose M8 when
The device is physically small, the current is under 4 A, and you need to pack connectors tightly together. Compact sensors, small actuators, camera housings and machine guards are the classic M8 homes.
Choose M12 when
You need Ethernet (D-coded or X-coded), more than 4 A of power (L-coded), frequent connect and disconnect, or a plant that already standardises on M12 tooling. M12 also survives more handling, which matters on cables operators touch every shift.
The honest summary
M8 saves space and a little money. M12 buys you current, Ethernet and robustness. Most plants end up with both: M12 for the backbone and devices, M8 for the tight spots. If you’re standardising a new machine, default to M12 and reach for M8 only where the size forces it.
Not sure which fits? Send the drawing and we’ll call it.