First you need to determine if you have the correct size motor. Then the supplier of the motor should be able to give you prop recommendations. The size of the motor depends on how you want to fly. Here are some guidelines that may help. It’s the total flying weight of the plane that you need, including motor and battery.

You'll need to weigh the plane and estimate the weight of the motor and battery.

• 50 to 70 watts per pound is the minimum level of power, good for park flyers and lightly loaded slow flyers.

•70 to 90 watts per pound is perfect for trainers and slow-flying aircraft.

•90 to 110 watts per pound is good for fast-flying scale models and some sport aerobatic aircraft.

•110 to 130 watts per pound is what you want for advanced aerobatics and high-speed aircraft.

•130 to 150 watts per pound is needed for lightly loaded 3D models and ducted fans.

•150 to 210+ watts per pound gives unlimited performance for any 3D model.

Once you have the size of motor. If you want to fly fast, pick a higher Kv motor with a lower diameter higher pitch prop. If you want to fly slower pick a lower KV motor with a larger diameter, lower pitch prop.