I've always been given to understand that it's the boat's windage (vs. displacement) that determines what size ground tackle you need. That makes me think that it's also windage that is the main factor in how much pull is on your anchor.

For calculating windage and how much force a given sized boat puts on the chain, there are some good instructions in "The Capable Cruiser" by Lin and Larry Pardey. They explain how to figure out your boat's windage, and how to calculate the potential force put on the ground tackle by it.