Disclosure: This guide is written by LUGGEX and compares four carry-ons we sell. We may earn revenue if you buy through the links below. Instead of calling every suitcase “airline approved,” we compare the full exterior measurements—including wheels and handles—with airlines’ published limits. Final acceptance is always up to the airline, aircraft, fare, and gate team.
Choosing between the ZX 20, ZX All-in-One, ZX 21, and ZX 22 comes down to one question: do you want the broadest possible airline fit, faster laptop access, more packing room, or maximum capacity?
Here is the short answer: the ZX Carry-On 20-inch is the closest of these four to the common U.S. carry-on standard. The ZX All-in-One and ZX Bigger Carry-On 21-inch make more sense when your airline publishes a larger allowance. The ZX Carry-On 22-inch prioritizes space and carries the greatest gate-check risk.
For a deeper explanation of how airlines measure bags, read our 2026 Carry-Ons Compare luggage size guide.
Which One Comes Closest to Fitting Most U.S. Airlines?
The ZX Carry-On 20-inch is the best bet of these four for broader U.S. airline use, but it is not a guaranteed fit. American, Delta, and JetBlue publish a 22 × 14 × 9-inch maximum, including wheels and handles.
The ZX 20 matches the 22-inch height but is 0.6 inch over in both width and depth. Because it is rigid, do not assume it can compress into a baggage sizer.
“Closest fit” is not the same as “within every published limit.” Check your airline before departure and be prepared for possible gate checking.
Which Models Work Better With Larger-Allowance Airlines?
Southwest and Frontier publish a 24 × 16 × 10-inch maximum. On paper, the ZX 20, ZX All-in-One, and ZX 21 fall within that envelope.
Pick the All-in-One for a slim-laptop compartment or the ZX 21 for more flexible packing. Size eligibility does not mean a bag is included with every fare; Frontier may charge for an overhead carry-on.
The ZX 22 is designed around this larger category, but its full listed dimensions—24 × 16 × 10 inches—are maximum carry-on space. It can be accepted in Southwest and Frontier Airlines.
The Best Model for Each Type of Traveler
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ZX 20 — widest practical airline use: Smallest footprint and a 36-liter interior, but no dedicated laptop door and still slightly over the common 22 × 14 × 9-inch rule.
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ZX All-in-One — business travel: Quick access for a slim laptop up to 16 inches, plus a cup holder and bag hook. Its 10.5-pound empty weight is the highest here.
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ZX 21 — flexible packing: The lightest model in the comparison with more room than the ZX 20. Best for larger-allowance airlines or ground travel.
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ZX 22 — maximum capacity: A listed 50 liters for longer trips, but the least airline-flexible option. It is better when checking is acceptable or for car, train, and cruise travel.
Our Honest Recommendation
If you fly several airlines, start with the ZX 20—but verify your itinerary. If you mostly fly Southwest or Frontier, choose the All-in-One for laptop access or the ZX 21 for flexible packing. Choose the ZX 22 only when you understand its slight size overage and are comfortable with possible checking.
Before buying, compare the live specifications on each product page and read the current Returns & Exchanges and Warranty Policy. Airline rules change, and honesty about fit is more useful than an “approved” label.
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