Get yourself a 34-36" stick and drive it into the ground next to your bait so that it protrudes 30". If the back is level with the stick when standing on all fours, the bear will weigh at least 250# dressed weight. Definitely not a boo-boo bear or yearling adult.

A DNR bear technicial once told me that as soon as the front paw print gets to 5.5x6.5", the bear will be upwards of 250#. However, it could be 400# too! Hard to measure from a stand obviously. The best route is the stick.