Does anybody know the max size of carry-ons allowed by most airlines? I realize that they vary somewhat.

During a recent visit to the US I was amazed by the size of carry-on bags (huge suitcases) that seem to be tolerated by domestic airlines there. They would definitely not get away with it here in Europe, where check-in staff ask to see passengers' hand baggage and sometimes weigh it.

Yes, the rules on hand baggage vary from airline to airline. As a general rule, the low-cost airlines are the meanest with hand-baggage allowance - Ryanair, for example, restricts hand-baggage to 7kg and has dimensional limits too.

I suggest you check with the airline(s) you plan to fly with if you are concerned. As a guide, I generally take a small/medium sized backpack (dimensions, in centimetres, about 20 x 32 x 35 when fully expanded) as hand baggage when I want to do a short trip somewhere without checked baggage, and so far this has been accepted by all the airlines I've flown with.

Pete

I fly Jet Blue on a regular basis, and I'm amazed when i see the carry-on bags that people take on board...I've seen people with three bags: a computer bag, a small suitcase, AND a medium size duffel bag. With jet blue, i actually prefer to check most of my stuff except for the extremely valuable items because there isn't enough overhead luggage space.