The additional luggage should be less than 50 pounds in weight and 62 inches in size of United Airlines Baggage Policy . Customers flying out of any U.S. airport may transport United Airlines carry-on luggage through security and board the plane with:- Trial-size liquids, Every liquid item having 3.4 ounces or less. Know everything about United Airlines Baggage Policy, United Airlines Baggage Allowance and Fees 2021-2022 and recommendations from past passengers.