Educated guess with an actual deer down on the ground, where body size, rack size and the teeth can be examined using 32 years of hunting experience. Even then it's still a guess, although it is much more certain than by looking at a picture. It really is the only way I've found to have any level of certainty, since pictures are pretty much worthless, thus my original guess of 1.5 or 2.5 years old. That's my two cents on it.