I use the 55 gallon bait barrel to compare the size of the bear, if he is smaller than the barrel, he is a young one, If he dwarfs the barrel he is a keeper
You can also tell bye the size of the head, if the head is big and blocky,ears look almost too small for the size of the bear, its a good size bear, if the ears look like mickey mouse, it is a young bear. After many years being seasoned to seeing bears and knowing there size bye a glance, this takes a while for you get a natural ability to know if it is a true trophy, bears tend to look bigger than they are for the most part, look for the belly to be bloated and hang lower to the ground, legs look stubby and wide, not long and slender, these are just a few tips how to judge a bears size,Look for a sway to there walk, males tend to walk front toe's inward, sometime its is hard when the light levels are low. Aim small hit small. RAMbo.