Southwest Personal Item Size: What Actually Fits in 2026

Southwest's official wording allows one smaller, personal type item, purse, briefcase, laptop case, or backpack, that can be stowed under the seat in front of you, in addition to your carry-on bag. There's no dimension attached to that description anywhere on Southwest's fee page or its carry-on baggage policy article. It's a functional description, does it fit under the seat, not a measured limit.

That's a genuine gap compared to most other major U.S. carriers. American Airlines, Frontier, Allegiant, and United all publish an exact personal item size in inches. Southwest, along with Delta, Alaska, Hawaiian, and Emirates in our data, allows a free personal item but states no measurements for it at all.

Southwest's carry-on is exact: external dimensions of 10 x 16 x 24 inches, including wheels and handles, free on every fare. That figure is published clearly and repeated consistently across Southwest's own fee and policy pages.

The personal item simply isn't held to the same documented standard. Southwest checks it functionally, by whether it fits under your specific seat, rather than against a printed box the way the carry-on gets sized at the gate. That makes the personal item more of a judgment call at boarding than a hard-and-fast measurement, which is exactly why no number exists to quote.

Since there's no official Southwest number, the practical approach is packing to a size that clears the tightest published personal item limits among the airlines that do state one. Among the carriers in our data, Avelo and Sun Country both publish 17 x 13 x 9 inches, and United's is narrower still at 17 x 10 x 9 inches. A bag at or under roughly 17 x 13 x 9 inches has cleared the smaller end of what other airlines require under a seat, which is a reasonable stand-in for a Southwest seat as well.

This isn't a Southwest figure, and no site can honestly present it as one, since Southwest doesn't publish it. It's a conservative benchmark built from what comparable carriers do measure, offered because packing to nothing at all isn't a real option before a flight.

If you search for a specific Southwest personal item size and find a number, it's a community or forum estimate, not Southwest policy. Southwest's own help center article is explicit that the item just needs to be small enough to stow under the seat, with no dimension attached, so any exact figure attributed to Southwest directly should be treated as someone's guess rather than an airline rule.

That's worth knowing before you buy a bag advertised as sized specifically for Southwest's personal item, since there's no official spec that product is actually being built to. A bag marketed that way is being sized against the same kind of estimate this section just described, not a number Southwest itself publishes.

Because Southwest's carry-on allowance, 10 x 16 x 24 inches, is bigger than most other airlines' carry-on limit and comes with no weight cap, the personal item matters less on Southwest than it does on an airline where the carry-on is stricter. Packing your heavier or bulkier items into the roomy carry-on and keeping the personal item to something genuinely small and soft avoids the under-seat guesswork almost entirely.

If your itinerary mixes Southwest with an airline that does publish a tight personal item limit, like United's 17 x 10 x 9 inches, pack to that airline's stricter published number rather than guessing at Southwest's unpublished one, since a bag that clears the documented limit will clear Southwest's judgment call too.