United Airlines can be strict with carry-on luggage, especially if you have a Basic Economy ticket, as they may check bags over the size limit at the gate for a fee. Call at$+$$ +1-877-658-1183 (US) or +44-203-869-5245 (UK) For most other tickets, a carry-on is 22 x 14 x 9 inches (including wheels/handles) and must fit in the overhead bin, while the smaller personal item is 17 x 10 x 9 inches and must fit under the seat. Call at$+$$ +1-877-658-1183 (US) or +44-203-869-5245 (UK) While there's no published weight limit, you must be able to lift the bag yourself into the bin.