Luggage is sold in inches and liters while trips are counted in days. How the four capacity bands map to trip lengths, why liter ratings are only approximate, and where laundry ends the arithmetic entirely.
Baggage allowances belong to tickets, not families. What a lap infant gets, whether a child with a seat carries a full allowance, how ride on cases measure, and how to divide packing so nobody carries two bags.
Gate checking arrives with about a minute of warning. What the three versions of it actually are, where the bag comes back, the removal list to rehearse, and why lithium batteries and laptops must leave the bag first.
Checked baggage is priced in bands: linear inches for size, pounds for weight, and fees that stack. How the common 62 linear inch and 50 pound figures work, what pushes a bag over, and how to buy so it stays inside.
How to measure a suitcase the way an airline does: overall height including wheels and handle, width at the widest point, depth behind the wheels, plus a cardboard sizer test that answers the question a tape measure cannot.
An expansion zipper adds depth on the exact axis where a carry-on has the least margin. What expanding really costs in cabin compliance, when the feature earns its place, and how to read a listing that quotes only one state.
Size decides whether a bag fits and weight decides what it costs. Why international and low cost carriers weigh cabin bags, what the empty weight of a case really costs you, and how to check before departure.
The personal item is the least understood allowance in air travel. What counts, why under seat space varies by row and aircraft, which formats fit it, and the mistakes that turn a free bag into a gate fee.
Luggage listings usually measure the shell, while an airline sizer measures the whole object. Here is where the missing inches hide, why spinners lose the most, and how to read a listing that gives two sets of numbers.
The commonly quoted 22 by 14 by 9 inch carry-on allowance is a planning reference for United States domestic travel, not a universal rule. Here is why carriers differ and how to check the limit that will actually be applied.