Size of backpack

Q: I am going backpacking in Europe from July and would prefer to travel with a backpack that I don't have to check in when I fly adn can use as carry-on luggage. What are the restrictions on size? - John Levitt

A: The guidelines for carry-on luggage in EU countries specify that it cannot weigh more than 10kg or be larger than 55cm x 40cm x 20cm. This means that a 45L backpack, which you would need for an extended trip, would be too big to carry on the flight. It may be better to check in your backpack, but valuables and essentials in a detachable bag, which you could carry with you on the flight.