Enter your bag once and see every airline it clears — and, more usefully, the ones it does not and by how much.
Enter your bag once. We check it against every airline whose allowance we have verified, and tell you where it fails rather than just whether it passes.
Measure the bag as it travels: wheels, handles and any expanded section included. That is how it is measured at the gate.
Manufacturers quote the body of a suitcase. Gate agents measure the object you hand them: wheels, feet, handle housing, and the expansion zip if you have opened it. A bag sold as 22 x 14 x 9 in is routinely 23 x 15 x 10 in once those are counted, which is exactly the margin that gets it pulled at the gate.
Stand the bag upright against a wall and measure each dimension at its widest point, including anything that sticks out. Those are the three numbers to enter above.
There is no universal carry-on size. The 22 x 14 x 9 in figure common in the United States is a convention rather than a rule, and much of Europe and Asia works to smaller boxes and to weight limits the US carriers do not enforce at all. A bag that has flown domestically for years can fail on its first budget European sector.
So the useful output is not a verdict. It is the specific carriers where your bag fails and the dimension that fails on each, because that tells you whether you need a different bag or just a different airline.
These numbers compare rigid measurements. A soft-sided bag with give in it will often pass a sizer it fails on paper, and a hard shell an eighth of an inch over will not. If your bag is close on one dimension and soft, it will probably be fine. If it is over on two, it will not.