Inrunner vs Outrunner Motors: What’s the Difference and Which One Should You Choose?

The rotor, or spinning component, of an inrunner motor is housed inside the stator, or stationary coils. The design of this is comparable to that of conventional brushed motors.

Pros:

• High RPM: Inrunner motors are known for their high rotational speed (RPM), making them perfect for high-speed applications.

• Efficiency: Generally more efficient at high RPMs with lower internal resistance.

• Enclosed Design: The rotor is shielded inside the stator, offering better protection from dust or debris.

Cons:

• Lower Torque: They produce less torque than outrunners of the same size, often requiring a gearbox or transmission to increase torque.

• Cost: Inrunners are often more expensive due to precision engineering and cooling requirements.

Best For:

• RC cars with gear reductions

• High-speed drones and jets

• Industrial applications requiring compact form factors

• Electric skateboards (with gearboxes)

Since the rotor of an outrunner motor is located outside the stator, the motor's outer shell rotates.

Pros:

• High Torque: Outrunners produce significantly more torque at lower RPMs, which is great for direct-drive applications.

• Simpler Setup: Often doesn’t need a gearbox due to high torque, saving on space and complexity.

• Cost-Effective: Generally more affordable and easier to manufacture.

Cons:

• Lower RPM: Doesn’t spin as fast as inrunners, which can limit top speed in some cases.

• Open Design: Exposed rotor can be more susceptible to damage from debris or impacts.

Best For:

• Drones (especially multirotors)

• Combat robots

• Electric bicycles and scooters

• Gimbals and camera stabilizers

• Direct-drive applications