never checking in luggage when flying
Ideally, your bag should be 48cm by 34cm by 23cm as that will fit in most overhead compartments. But while that may be the size when you buy, you have to be careful of protrusions like exterior pouches, which can push you over the size limit.
Consumer Reports also stresses good-quality wheels for your bag. Spinner bags (those with four wheels for easy manoeuvrability) are best, but these wheels can break. Before buying, make sure your spinner wheels are attached to the bag with screws, not rivets.
The full video has many other neat tricks and is worth checking out. Once you have your bag, here’s how to fit up to two weeks of luggage into it.
Carry-On Luggage Buying Tips [Consumer Reports]