Flying with the United Air means, you need to check the information about the United Airlines Carry-On Baggage Policy for your travel plans. Only one personal item and one carry-on item are allowed for on-board baggage in this airline. The carry-on bag must be fit in the overhead bin space for the passengers and the maximum allowed dimensions for the carry-on baggage are 9 inches x 14 inches x 22 inches (22 centimetres x 35 centimetres x 56 centimetres). This includes handles and wheels.
Personal item must be fit underneath the seat in front of passenger and the maximum allowed dimension for the personal item is 9 inches x 10 inches x 17 inches (22 centimetres x 25 centimetres x 43 centimetres). Here is also the list of those items which are allowed to carry in addition to your one personal item and one carry-on bag, you can bring on board;