This is RYANAIR's hand luggage policy, but there may be differences for other companies. "Carry-on luggage weighing up to 10 kg and measuring 55 cm x 40 cm x 20 cm and a small bag of up to 35 cm x 20 cm x 20 cm may be carried on board per passenger *. ) is not allowed, but a changing bag weighing up to 5 kg is carried by the adult outside his / her own hand luggage. Extra / overweight carry-on baggage will be refused at the boarding gate or, where available, will be placed in the hold of the aircraft for a fee of £ 50 / € 50 (charges may apply for VAT on domestic flights) . carried by an adult outside their own hand luggage is permitted if the infant (between 8 days and 23 months of age) is traveling on the lap of an adult traveling with him / her Smaller instruments such as cello, git price, the violin or the viola, which exceed the hand luggage sizes we require, may be carried on board the aircraft with the reservation of a seat for that purpose and payment of the appropriate fee. The booking of such a seat does not involve the weight of checked baggage per passenger. When booking a seat reserved separately for such an item, enter "ITEM SEAT" in the "last name" category and "EXTRA" in the first name category. This will display "EXTRA ITEM SEAT" on both your booking and boarding pass. When checking in online, the details of the accompanying passenger's travel document must be provided. It is not possible to buy seats in lines 1, 16 and 17 at the emergency exit if you have already purchased a separate seat for convenience. "