Originally Posted by
Flying for Fun
The seat belt doesn't go all the way around your waist. It is attached at each side and anchors you across your lap. If your waist is 40", hip to hip across the front would be 20". If we add 2" on each side for tethering to the seat frame, we will have used about 24" of the 31" length. The seat belt should accommodate a waist up to about 54".
Most humans only carry a spare tire in the front, not front and back, so the front-side measurement will be slightly more than backside.