Bests & Worsts Reviews from Amazon

This bag easily fits under the seat: tested under both a window seat and aisle seat on Southwest Airlines' 737s. The picture shows it under the aisle seat. The trick is not to fill it so full that it is bulging. If you fill to capacity but the outside is relatively flat and not rounded, it will fit, no problem. Some airlines have entertainment systems under the seat which crowds-out space for your luggage. I didn't test that scenario yet. There was some space on the side, on our Southwest Airlines flight, which suggests it may squeeze in, even if there's an entertainment system mounted under each seat.