To figure the cutting surface I take the cutting diameter and divide it by two, then multiply the number of blades by that figure. I then add in any cut on contact tips or blades that are not full size.
This is hardly a "cutting surfacee" figure you come up with at the end. It's simply a different way to give it some arbitrary figure. I guess it's OK if you do the all the same, but it's hardly CUTTING SURFACE. The major contributor to this total is number of blades. I guess it works, but I can see it giving false hope. For example, the old Rocky Mountain Razorbacs with the 5 blades. Through it all it's a ho hum broadhead.... but 5 blades really boost the number in a misleading way. In fact, it's really a crappy broadhead. Too small a cutting diameter that leaves terrible blood trails. I think I shot probably a dozen deer with them before I decided they did it every time.
Hey Newman.... I've killed a lot more deer than I have barrels and probably used a dozen different broadheads in the process. What will you pay me for my test results.[8D][8D][8D] Field tested .....Blue Undies guaranteed.