bag vs limit
4.8" to spareTopo Designs Rover Pack Mini
13.5 × 8.5 × 3.75 inEnormous margin against every limit here, and it looks like a normal bag rather than travel gear. Ten litres is a daybag though, not a travel bag.
Southwest Airlines publishes no personal item dimensions at all. The only test is whether the bag fits under the seat in front of you. We use 18.5 × 13.5 × 8.5 inches as a working estimate to filter bags — it is our figure, not Southwest’s.
Measure the outside, wheels and handles included — that’s what they measure at the gate.
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Enormous margin against every limit here, and it looks like a normal bag rather than travel gear. Ten litres is a daybag though, not a travel bag.
The anti-theft option that actually fits — slash-resistant panels, locking zips, RFID pocket, and a 13-inch laptop sleeve, all inside United’s width.
Pacsafe’s own site is JavaScript-gated, so this comes from a retailer spec rather than the brand. The 0.2 inches of width margin rests on that number.
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.
Unstructured, so 7.48 inches is the empty depth. Pack it full and it rounds out.
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.
Buy the MEDIUM. The Large is 16.5 × 11 × 9 and fails United on width.
A tote-shaped answer to the Narwey. Under a pound, folds flat, and doubles as a packable second bag stuffed inside a bigger case.
The cheapest bag here we can fully stand behind. Cabin Max publishes 40 × 25 × 20 cm as the external size, and 40 × 25 × 20 works out to exactly the 20 litres they claim — when the arithmetic agrees with the marketing, the numbers are usually real. No wheels, so the usual “does that include the wheels” ambiguity doesn’t apply. Three-year warranty.
9.84 inches against United’s 10-inch limit is about a sixth of an inch of margin. It’s a soft bag and it will bulge — pack it full and it may not gauge.
Sold as a “17x10x9” bag but the manufacturer’s own spec is 40 × 25 × 20 cm — meaningfully smaller than the limit, which is exactly what you want. Clears United and the budget carriers both, for under thirty dollars.
At 0.77 lb this is a thin packable, not a structured daypack. Treat it as a very good backup bag rather than your only one.
A rare expandable that stays legal even when expanded — 5.9 inches deep collapsed, 7.9 expanded, and still inside United’s limit either way.
Don’t confuse this with COSCOOA’s expandable tote, which grows to 13 inches wide and busts United.
The version of the ECOHUB whose title states its real size honestly. At 7.9 inches deep it slips under the budget carriers’ 8-inch limit as well as United’s — a combination almost nothing else in this price range manages.
Sibling ECOHUB listings claim 17 × 11 × 8. Check the width on the exact one you buy.
The default cheap budget-airline bag. Genuinely undersized, so it clears even strict gate sizers, and it folds down to nothing once you’ve unpacked.
The listing title says 18×14×8 — that’s the airline allowance used as a keyword, not a measurement. The real bag is 18 × 13 × 6.3 and bulges past 6.3" when packed.
The shortest bag here at 16.5 inches, yet still 28 litres. That spare vertical headroom is what lets it clear a sizer with the depth right at the line.
Squeezes 30 litres into a personal item and adds a wet and shoe pocket. About the volume ceiling for a cheap budget-carrier bag.
Fills the 18×14×8 box almost exactly, so there is zero margin against a strict sizer.
The only bag we verified that fits United and still takes a genuine 15-inch laptop. Military-grade build from a brand that makes packs for people who abuse them.
Only a quarter inch of width margin — don’t overstuff it. Also 8.5 inches deep, so it misses the budget carriers’ 8-inch limit.
The one wheeled bag here that genuinely passes an 18×14×8 sizer — because the wheels pop off in a single click. Wheels on it’s 19.5 inches and fails; wheels off it’s 17.5 and passes.
The fit verdict shown assumes the wheels are removed. With them attached it measures 19.5 × 13.5 × 7.8.
The category’s cheapest and longest-standing default. It is completely unstructured, and that is the point — a soft bag at exactly the limit squashes into a sizer, which a rigid one at the same size cannot.
Fails Frontier and Allegiant on depth by an inch. No laptop sleeve, just a tablet pocket.
Hits the budget-carrier box exactly, in backpack form. Lay-flat clamshell opening and a detachable shoe compartment.
18×14×8 is a design target, not an independent measurement — reviewers report it runs over when packed full. MATEIN runs dozens of near-identical listings, so check the specs on the exact one you buy.
Fills United’s box exactly — 25 litres inside a 25.07-litre envelope, which is the only honest capacity claim in this whole category. Sixteen pockets, an AirTag pocket, 180° clamshell and a trolley sleeve.
Zero margin on all three axes, and the 9-inch depth means it fails Frontier and Allegiant’s 8-inch limit by a full inch.
Looking at the other size too? See Southwest carry-on sizes, the full Southwest baggage guide, or our picks for the best Southwest bags. Flying with a camera? 13 camera bags fit — see the camera bag guide.
| Basic Economy / cheapest fare | ✓ | Included. No US carrier has ever charged for the under-seat item. |
|---|---|---|
| Main cabin and above | ✓ | Included, same allowance. |
| Elite status / co-brand card | ✓ | No change — it was already free. |
Southwest Airlines publishes no aircraft-specific carry-on rule — the same limit is stated for its whole fleet. Only Delta, United and American publish rules that change with the aircraft, and we are not going to invent one for the others.
Wondering how big the bins actually are? Nobody publishes that — see what is actually known about overhead bin sizes.
Southwest Airlines does not publish one. The bag simply has to fit under the seat in front of you. We use 18.5 × 13.5 × 8.5 inches as a working estimate when filtering bags.
Yes, provided it fits under the seat. A packed backpack bulges, so measure it full rather than empty.
No. The personal item is free on every fare, including the cheapest ones.
Of the bags we track, 17 fit — 14 with room to spare and 3 borderline. 13 camera bags also fit.
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