Each traveler may bring no more than one bag of liquid carry-ons. It must be a 1-quart bag, and it must be made of clear plastic with a zipping top. Passengers must place the bag in the security bin along with other items like shoes, laptops and metallic objects, and send it along the conveyor.
A traveler can fill his 1-quart bag with as many liquid containers as can fit. The maximum volume of each container is 3.4 oz. A typical shampoo bottle, for reference, is about 13 oz. If you're in doubt about the legality of your liquids, consider placing them in checked baggage.
The Transportation Security Administration permits certain medically or nutritionally necessary liquids in volumes larger than 3.4 oz. These include baby formula, breast milk and medications. Passengers should declare these substances for inspection at the security checkpoint.
