Best carry-on size for US airlines
The carry-on size that fits the overhead bin across US airlines.
Fits the cabin bag allowance on all 11 reviewed airlines in this group. The tightest is United Airlines.
How to use this recommendation
The familiar US carry-on label hides small differences between airlines. This guide compares the overhead allowances of the major US carriers we have manually reviewed and calculates one outside size that remains within all of those published boxes.
The trade-off
The common result prioritises cross-airline compatibility, not the largest case accepted by Southwest or Frontier. Basic-economy and paid-bag rules can still change whether the overhead piece is included even when the physical dimensions fit.
How we calculated it
We retain the strictest compatible edge from every reviewed carrier after normalising bag orientation. Where an airline publishes inches, the source measurement remains decisive; centimetre values on FitsOnBoard are provided for comparison and may be rounded.
cabin bag limit per airline (11)
| Airline | Limit | Weight |
|---|---|---|
 United Airlines | 56 × 35 × 22 cm | — |
 Delta Air Lines | 56 × 35 × 23 cm | — |
 American Airlines | 56 × 36 × 23 cm | — |
| JetBlue | 56 × 36 × 23 cm | — |
| Alaska Airlines | 56 × 36 × 23 cm | — |
| Hawaiian Airlines | 56 × 36 × 23 cm | 11 kg |
| Allegiant Air | 56 × 41 × 25 cm | — |
 Southwest Airlines | 61 × 41 × 25 cm | — |
| Frontier Airlines | 61 × 41 × 25 cm | 16 kg |
| Spirit Airlines | 56 × 46 × 25 cm | — |
| Sun Country | 61 × 41 × 28 cm | — |
FAQ
What is the best cabin bag size for this group?+
A bag no larger than 56 × 35 × 22 cm (22 × 13.8 × 8.7 in), up to 11 kg fits the cabin bag allowance on all 11 airlines in this group — the limit is set by United Airlines.
Why not just buy the biggest bag?+
Because the strictest airline in the group wins. A bag that fits United Airlines fits everyone here; a larger one would be rejected or charged there. Buy for the tightest limit and you’re safe on all.
Should I leave a safety margin?+
Yes — measure with wheels and handles, and pick a bag a touch under the limit. A packed bag bulges, and low-cost airlines measure strictly at the gate.