I put two of my favorite carry-on bags to the test to see which one holds more! The clear winner was the CALPAK for under the seat. We brought the Beis Carry-On Roller with thenCalpak duffle. I also love the iFly suitcases from Walmart and can use one of the other bags as your under the seat bag. LTKKids LTKTravel LTKItBag