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M8 connectors suit compact spaces and simple sensor/actuator signals (3–8 pins, up to 4A). M12 connectors handle more pins (up to 12), higher data rates (Ethernet via D/X codes), and more power. Choose M8 when space is tight and signals are simple; choose M12 when you need more pins, Ethernet, or power.

M8 and M12 are the two most common industrial circular connectors, and engineers face the "which one" question on almost every automation project. Both are threaded, IP67-rated, and built for harsh factory environments — but they are not interchangeable. This guide breaks down the real differences so you can spec the right one without over- or under-designing.

The M8 connector uses an 8 mm threaded coupling nut. It is the compact option in the metric circular family.

• Pin counts: 3, 4, 5, 6, and 8 pins
• Typical current: up to 4 A (3/4 pins), lower at higher pin counts
• Voltage: commonly 30–60 V
• Standard: IEC 61076-2-104
• Protection: IP67 when mated
• Common uses: proximity sensors, photoelectric sensors, small actuators, confined-space wiring

Because of its small footprint, M8 is the default for tight panels, miniature sensors, and applications where a few signal or low-power lines are enough.

The M12 connector uses a 12 mm threaded nut and is the more versatile workhorse. Its defining feature is coding (A, B, D, X, T, S, K, L), which prevents mis-mating and assigns each variant a function.

• Pin counts: 3, 4, 5, 8, and 12 pins (some power codes fewer)
• Current/voltage: varies by code — A-code signal up to 4 A/250 V; power codes (L/T/S/K) reach 12–16 A
• Data: D-code for 100 Mbps industrial Ethernet, X-code for up to 10 Gbps
• Standards: IEC 61076-2-101 (and others by code)
• Protection: IP67 (IP68 options available)
• Common uses: sensors, actuators, industrial Ethernet (Profinet/EtherCAT), power distribution, robotics

If your design needs Ethernet, more pins, or meaningful power, M12 is the right call.

1. Installation space is tight (small sensors, narrow panels)
2. You only need a few signal or low-power lines
3. Cost per connection matters and Ethernet is not required
4. The device is a standard proximity/photoelectric sensor or small actuator

1. You need industrial Ethernet (Profinet, EtherCAT, Ethernet/IP)
2. The application requires more than 8 pins
3. You are transmitting power (not just signal)
4. Future expansion or higher data rates are likely

Not sure which coding your M12 needs? See our [M12 A/D/X coding guide] for the full breakdown.

They are mechanically different sizes, so they cannot plug into each other directly. Adapters and hybrid cables exist, but in new designs it is cleaner to standardize on one family per device function. Many machines use M8 at the sensor end and M12 at the controller/network end, joined by pre-made adapter cables.

Is M8 cheaper than M12? Generally yes — fewer pins, smaller body, simpler tooling. But the right choice is about fit, not price.

Can M8 carry Ethernet? No. Ethernet needs M12 D-code or X-code connectors.

Which is more rugged? Both meet IP67 when properly mated. Ruggedness depends more on housing material (metal vs plastic) and sealing than on M8 vs M12.

Do M8 and M12 share the same standards? They follow different IEC 61076 sub-standards (M8: -2-104; M12: -2-101 and related). Always check the specific code.

KRONZ supplies both M8 and M12 circular connectors across full pin counts and codings, with IP67 protection and IEC 61076 compliance. Contact our engineering team for samples, CAD files, and volume pricing.