Air Speed Calculator                        

The form below will calculate the speed at which a propeller will move through the air at a given RPM and Pitch.  This will give an approximate top speed and can help you decide which prop to use for a plane.  For example if your airspeed calculates to 150 MPH and your plane is a Lazy Bee, then you've got the wrong prop on your plane because there is now way that plane will do 150 MPH. (Slight exaggeration, but you get the idea.)  

RPM: 
Prop Pitch: 
Theoretical speed.

 

  • The pitch of a propeller denotes the inches of forward travel per revolution.
  • There are 63360 inches in a mile. There are 60 minutes in a hour. Airspeed is calculated as follows:
  • Pitch / 63360 = miles per propeller revolution
  • RPM*60 = revolutions per hour
  • miles per propeller revolution * revolutions per hour = miles per hour
  • OR
  • 63360 / 60 = 1056
  • RPM* Pitch / 1056 = miles per hour