07/09/2026
Nine airlines. Nine different limits. And none of them "approves" anything.
There is no such thing as an airline-approved carrier. Each airline publishes a maximum size for the space under the seat, and a gate agent decides on the day whether your bag fits it.
American allows 11 inches of height. Southwest allows 8.5. Alaska stops at 9.5. Same passenger, same bag, three different answers.
Swipe for the two that catch people out: Southwest, and the American Eagle rule that shrinks your limit mid-trip.
Every figure here was read from the airline's own policy page, and we re-check all nine every three months. The full table is on the site — link in bio, free, no email needed.
Which airline are you flying? Tell me below and I'll tell you what fits.
