3-1-1 for carry-ons = 3.4 ounce (100ml) bottle or less (by volume) ; 1 quart-sized, clear, plastic, zip-top bag; 1 bag per passenger placed in screening bin. One-quart bag per person limits the total liquid volume each traveler can bring. 3.4 ounce (100ml) container size is a security measure. Be prepared.