Buy your usual waist size, then cinch the drawstring.

Swim trunks are sized like regular shorts—buy the waist size you normally wear. The drawstring is there to dial in the fit, not to rescue trunks that are two sizes too big. If you go too large, the fabric bags out and looks sloppy even when pulled tight. Too small, and you’re fighting the string for no good reason.

The real variable is length. Most brands fall between 5 and 9 inches inseam. If you’re not sure, 7 inches is the Goldilocks — not dad-short, not board-short long. Try them on with nothing in the pockets so you get the real fit.

Don’t overthink this one. The drawstring does the heavy lifting.