If you are going to be able to figure energy, you must have a chrono, the formula is velocity squared times mass(weight of bolt) divided by 450240 that will give you ft/lbs, all things being equal, that will give you penetration....Do not be fooled by the makers claims of speed, most of "them" lie to bring in more customers............The ones that have been the closesest to their claims have been Excalibur and Bear both of these bows have actually shot faster for me thru the chrono.If fact both shot(Bear340&Exomag) almost the same, both were over 370fps with Golt Tip Lazer2 bolts with carbon inserts and carbon bolt endsand 75g points.......