Our Kahoots (45 litre) fits within the carry on parameters of most major airlines.Maximum dimensions for carry on allowances vary across the different airlines but many of our customers have also reported taking their Kahoots (58 litre) as hand luggage without incident as long as it's not packed full.Unlike a hard case, our Leisure Bags can be compressed to fit into overhead compartments, so we suggest slightly underfilling it to allow flexibility to meet the constraints for your specific carrier.For current allowable carry on baggage sizes, please check with your airline.