Southwest allows 24 × 16 × 10 in in the overhead bin and 18.5 × 13.5 × 8.5 in under the seat (our estimate — they publish none). These are the bags that fit those numbers with the most room left over, ranked.
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Built to maximum-legal geometry on purpose. The flat 22 × 14 × 8 box wastes almost no sizer volume, and it’s the only backpack here strictly inside 22 × 14 × 9 on all three axes.
Exactly 22 × 14 × 9 overall — genuinely legal with the wheels counted, which almost no other "20-inch" bag can claim. Lightest in this group, and it expands two inches.
A pound and a half for 45 litres inside a legal carry-on footprint, and it converts to a backpack. Nothing else here comes close on weight.
The reference point for one-bag travel. Suspended mesh backpanel, stowaway harness, a proper hipbelt, clamshell opening.
The cheapest credible hardside spinner and the default budget answer. Expands about 25 per cent, and the published dimensions explicitly include the wheels.
Routinely under $60, with eight multi-directional wheels and a five-year warranty. Nothing fancy, but it does the job.
Five ounces. It stuffs into its own pocket, so it costs you almost nothing to carry as insurance — and it clears every personal item limit on this page.
The most margin of anything here — comfortably inside United’s brutal 17 × 10 × 9 and inside the budget carriers’ 18 × 14 × 8 too. Structured neoprene that holds its shape instead of sagging.
Want the full list rather than the picks? See every bag that fits Southwest’s carry-on limit or its personal item limit, or the complete Southwest baggage guide.
The Tortuga Travel Backpack Lite 40L at 22 × 14 × 8 in. Built to maximum-legal geometry on purpose. The flat 22 × 14 × 8 box wastes almost no sizer volume, and it’s the only backpack here strictly inside 22 × 14 × 9 on all three axes.
24 × 16 × 10 inches including wheels and handles. The personal item limit is 18.5 × 13.5 × 8.5 inches.
Not usually. Southwest’s limits are close to the industry standard, so most bags sold as carry-ons will fit. Check the depth, which is where bags most often fail.
Manufacturers publish dimensions inconsistently, and a “20-inch” spinner is almost never 20 inches once you count the wheels. Where a brand states dimensions including wheels and handles, that’s the number we use. Where it only publishes the case, we say so on the card. Airlines measure the outside of your bag — wheels, handles, straps and all. Anything marked borderline is down to the gate agent, and remember that a soft bag squashes into a sizer while a hard shell won’t.
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Limits verified August 2026 against each carrier’s published policy. Airlines change these without notice — always confirm before you fly. Spirit Airlines ceased operations on 2 May 2026 and is no longer listed.
Airline Bag Size Checker v1.0.15 · last updated 2026-08-12