When you measure cutting diameter that is at the base of the blade, the max OD (outer diameter) of the broadhead. Which assuming the shaft is about 1/4" then the part of the blade (perpendicular to the arrow shaft) would have to be about 7/16" (.25 + .4375 + .4375 = 1.125)
which would be 4 x .4375 = 1.75 + .25 = 2" cutting surface? (.25 being the assumed shaft diameter)

But if you look at the length of the sharpened part of the blade it looks to be almost twice the length of the bottom of the blade (the part that gives you the cutting diameter)

So, what I am asking is the cutting diameter what gives you the cutting surface measurement, or is it the actual measurement of the sharpened surface, which if the simple visible (assumed of course) ratio of 2:1

assuming a sharpened blade length of .875" x 4 = 3.5" of actual cutting surface.

Which gives you a cutting surface of 3.75" (when adding the .25" of the shaft diameter)





Now assuming any of that made sense up above, following the same logic, a 1 1/8" diameter Montec, if you look at the sharpened edge of this blade it looks to be almost 3 times the radius of diameter...so would the cutting surface on something like this be in the neighborhood of (assuming .25" shaft diameter)

7/16 x 3 x 3 = 3 15/16" + shaft diameter = 4 3/16" cutting surface......
7/16 = original blade radius
1st 3 is blade looks to be 3x the original blade radius
2nd 3 is for the 3 blade design.

Ya, I know this makes absolutely no difference in the scheme of anything, but I am just curious on how the math works, just wait until I get some time to question how or even why range finders are needed to compensate for elevation.......