ok here we go again! this is how youfigure out the kinetic energy of you're arrow. first you need to know the speed of the arrow. then you have to know the weight. here is the formula for figureing out the kinetic energy of you're bow&arrow.MULTIPLY SPEED X SPEED XWEIGHT DIVIDED BY 450240. HERE IS AN EXAMPLE 260FPS X 260FPS X415ARROW WEIGHT EQUALS 62.30 FT LBS OF KINETIC ENERGY OF THAT ARROW. HOPE THIS HELPS ALSO THIS WILL HELP YOU IN PICKING OUT THE BROADHEAD TO SHOOT ALSO. IT IS RECOMMENDED THAT 65FT LBS OF KINETIC ENERGY BE USED ON MECHANICAL BROAD HEADS OR HIGHER THAN 65FT LBS.GOOD LUCK. JIM