M8 or M12 Connectors - Which Fits Your Sensor?

What sets M8 and M12 apart?

M8 and M12 refer to the metric thread diameter of the coupling nut: 8 mm and 12 mm respectively. Both are standardised in IEC 61076‑2, screw-locking and typically sealed to IP67 when mated, up to IP69K in rugged versions. The differences lie in size, possible pin count and current rating.

M8 is the compact choice for small proximity switches and tight mounting spaces. M12 is the more rugged industrial standard with higher current rating and more pins, which is why it dominates most sensor and actuator cordsets today.

How many pins and how much current do you need?

Pin count follows the number of signals on the sensor. A simple PNP proximity switch needs 3 pins (L+, L-, switching output), a sensor with two outputs or IO-Link needs 4. Analogue and multifunction sensors use 5, complex devices 8 or 12.

• 3-pin: standard proximity switch with one switching output.
• 4-pin: two switching outputs or IO-Link communication.
• 5-pin: analogue signal (0‑10 V / 4‑20 mA) plus supply.
• 8-pin: safety and multi-signal sensors.
• 12-pin: encoders and complex measuring devices.

Current rating drops as pin count rises, because the contacts get smaller. An A-coded M12 carries about 4 A per contact at 3 or 4 pins, but only around 2 A at 8 pins. Always check the datasheet and allow for derating at high ambient temperature.

Which coding does the application need?

The coding is the mechanical shape of the contact carrier and prevents mismating between different signal types. It defines what a connector is intended for. The most important codings are A, B, D and X.

For classic sensing the A-coding is the standard choice. For networking the data rate decides: D-coded for Fast Ethernet up to 100 Mbit/s, X-coded for Gigabit and above. There are also L- and S/T-codings for power that should not replace A-coded signal cordsets.

Frequently asked questions