Pack Lighter with Our 18.104.22.168.1 Rule: Bon Voyage! All of these items would definitely fit into a carry-on, & if you've got access to a washing machine, you could make these clothes last for 2 weeks. The 1-bathing suit rule would be hard to stick to, especially for beach vacations, because if you're washing 1 suit, it might not be dry by the next morning. ;) I'd revise that to 2 suits, just to be on the safe side. Plus, they really don't take up much room in your luggage, especially bikinis.