The propeller pitch, or prop pitch, depends on the diameter and the pitch of the boat or aeroplane. The diameter is determined by the revolutions per minute at which the propeller will be turning and the amount of power need to turn the propeller. The pitch is the distance a propeller moves and the amount of power needed to turn the propeller. The pitch measures the distance a propeller will move in 1 revolution, according to the Boating Magazine website. Prop pitch needs to be understood before you decide to purchase a new propeller.

Measure the distance from the prop shaft to the pitch station with measuring tape. The propeller shaft is the pole that connects to the pitch station. The pitch station is the middle of the propeller or the part of the propeller that the blades are connected to.

Measure the pitch angle or the angle of the propeller's blades at a horizontal plane. The protractor should be at a flat 180 degrees on the pitch station. Look through the protractor to see what angle the propeller's blade goes through.

Access the Indoor Duration website's Prop Pitch Calculator (see References). Type your measurements into their respective boxes. Make sure the prop shaft is in inches and the prop blade angle is in degrees. Complete the calculation by pressing the “Calculate” button. The calculator will compute the prop pitch needed.