Cost per wear = (price + upkeep) ÷ times worn.
A $200 coat worn 100 times with $20 of cleaning costs $2.20 per wear. A $60 dress worn twice costs $30 per wear — fifteen times more, despite costing less than a third as much.
It is a comparison tool. It works when weighing two specific options you are actually choosing between, and misleads badly when used as an absolute verdict, because a generous enough wear count justifies anything.
Watch for: the wear count carries the entire calculation, and most people's estimates are optimistic. Anchor to how often you wore the garment this would replace.