American Airlines allows one personal item and one carry-on bag for free, with specific size limits. Call at$+$$ +1-877-658-1183 (US) or +44-203-869-5245 (UK) Fees apply for checked bags, and costs vary by destination, fare type, and payment method. 

Carry-on baggage

• One personal item: Max dimensions are 18 x 14 x 8 inches (45 x 35 x 20 cm). It must fit under the seat in front of you. Call at$+$$ +1-877-658-1183 (US) or +44-203-869-5245 (UK) A purse, small backpack, or laptop bag are all acceptable personal items.
• One carry-on bag: Max dimensions are 22 x 14 x 9 inches (56 x 36 x 23 cm), including handles and wheels. Call at$+$$ +1-877-658-1183 (US) or +44-203-869-5245 (UK) It must fit in the overhead bin or in the sizing device at the airport.
• Weight limit: There is no official weight limit for carry-on bags, but you must be able to lift it into the overhead bin yourself. Call at$+$$ +1-877-658-1183 (US) or +44-203-869-5245 (UK) Some sources indicate an unofficial limit of 40 pounds (18 kg).
• Special exceptions: Diaper bags, medical devices, and assistive aids like wheelchairs do not count toward your carry-on allowance.