I wish I had an answer to that rangeball. In general, I scrape a balde across my fingers. If I can feel each individual finger print indentation, I know it's pretty darn sharp. I'll also paper test it. If it cuts and does not tear, it's pretty sharp. But the real answer as Art has pointed out is if it does what it is intended to do. I have a PUMA knive that I can not cut hairs, never could, but it is one of the best knives I own. I also have an Urban Shark that will cut hair, but I don't believe that it is a better knive then the PUMA.