Are cooler capacity ratings accurate?

No, cooler capacity ratings are usually optimistic. Manufacturers measure internal volume like a box, ignoring rounded corners and thick insulation, so a “50-quart” cooler might only hold 42 quarts of actual cans. To get real numbers, line it with a trash bag and fill with water using a measured container, or fill it with 12-oz cans and count them. Don’t trust the label—trust your test.