bag vs limit
1.5" 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.
United Airlines allows a personal item up to 17 × 10 × 9 inches. That measurement includes wheels, handles and straps, and the bag has to fit fully under the seat in front of you. It is free on every fare.
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 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.
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 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.
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 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.
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.
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.
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.
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.
The one wheeled bag in the US market narrow enough for United, and the published figure already includes the wheels and handle. Every other underseat roller is built wide and short, which puts them 3–4 inches over on width.
Zero margin on every axis, and being rigid it can’t compress the way the soft version does. Tablet sleeve only, and the wheels eat a lot of the interior.
Looking at the other size too? See United carry-on sizes, the full United baggage guide, or our picks for the best United bags. Flying with a camera? 6 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. |
| Worth knowing | ! | On United Basic Economy the personal item is the only bag you get, so it carries the whole trip. That is the fare where its 17 × 10 × 9 in limit actually bites. |
United Express is not one rule. On CommutAir-operated flights you are allowed one personal item only. Every other United Express operator takes a carry-on, but United warns space is limited — and on United Express a gate-checked bag may come back at the jet bridge rather than baggage claim. The personal item is unaffected — it is the one bag that always travels with you.
Wondering how big the bins actually are? Nobody publishes that — see what is actually known about overhead bin sizes.
17 × 10 × 9 inches, including wheels, handles and straps. It must fit fully under the seat in front of you and is free on every fare.
Yes, provided it fits under the seat and stays within 17 × 10 × 9 inches once packed. 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, 12 fit — 12 with room to spare and 0 borderline. 6 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