The best personal item bags
The under-seat bag is now the only free luggage on a lot of fares. These clear the published limits - and we say exactly which ones each clears.
By Michael W. · Last updated September 24, 2026
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The personal item allowance has quietly become the most valuable thing on a lot of tickets. On United and Delta Basic Economy, and on standard Frontier and Spirit fares, it is the only bag you get for free. That turned a laptop sleeve category into a real luggage category, and the products followed.
What makes this category awkward is that the limits are not consistent. American, Frontier and Spirit publish 18 x 14 x 8 inches. JetBlue publishes 17 x 13 x 8. United publishes 17 x 10 x 9, which most 'personal item bags' fail. Delta, Southwest and Alaska publish nothing. Every pick below is labeled with which of those it clears - see personal item size by airline for the full table.
Quick picks
The short list. Tap any row for the full write-up, including what each one is bad at.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 |  Cotopaxi Allpa 35L Travel Pack Clamshell opening and a square profile that fills the 18 x 14 x 8 box properly. | American, Frontier, Spirit | |
| 2 |  Osprey Daylite Plus Daypack Slim enough for 17 x 10 x 9, which eliminates most of this category. | United Basic Economy | |
| 3 |  Baggallini Carryall Travel Tote A tote sized for the under-seat space, with a sleeve for a suitcase handle. | Short trips and business travel | |
| 4 |  Patagonia Black Hole Duffel 25L Frameless and coated - it becomes whatever shape the under-seat space is. | Delta, Southwest, Alaska | |
| 5 |  Narwey Foldable Travel Duffel Bag Packs flat inside your main bag, comes out when the personal item is all you get. | Occasional Basic Economy |
The one that turns the allowance into a real bag
Cotopaxi Allpa 35L Travel Pack
If your airline publishes 18 x 14 x 8, buy the bag that fills that box rather than approximating it. A clamshell opens flat, so you can see and reach things while the bag is wedged under a seat - which is the whole difference between a usable under-seat bag and a bag you have to drag into the aisle.
The specs that decide it
- Clears: 18 x 14 x 8 - American, Frontier, Spirit, plus the no-figure carriers
- Does not clear: United's published 17 x 10 x 9
- Opening: Full clamshell with mesh internal compartments
Flaws but not dealbreakers
Over United's published personal item limit on depth and width, which is awkward given United Basic Economy is one of the main reasons to buy this category. Loaded to 35 liters it is also heavy to shove into place with a foot.
The one that clears the tightest limit in the US
Osprey Daylite Plus Daypack
United's 10-inch width is the specification that matters, and it rules out most bags sold for this job. If United Basic Economy is how you fly, buying an 18x14x8 bag marketed as universal is buying the wrong bag. A slim daypack clears United and therefore clears everything.
The specs that decide it
- Clears: United's 17 x 10 x 9, and every other published US limit
- Shape: Slim profile - width is the deciding dimension
- Compresses: Soft build squashes into a sizer under a firm push
Flaws but not dealbreakers
Modest capacity, and on an 18 x 14 x 8 carrier you are leaving free allowance unused. It is a daypack rather than a travel pack: top-loading, no clamshell, and no real packing organization.
The one that does not look like luggage
Baggallini Carryall Travel Tote
There are trips where you do not want to arrive looking like a backpacker - a business day trip, a city weekend, anything where the bag goes straight from the plane to a meeting. A structured tote with a trolley sleeve does the under-seat job and then behaves like a normal bag at the other end.
The specs that decide it
- Clears: The 18 x 14 x 8 envelope; check the model against United's tighter figure
- Feature: Trolley sleeve - slides over a suitcase handle instead of being carried
- Access: Open-top or zip-top, reachable while under the seat
Flaws but not dealbreakers
A single-strap tote carried on one shoulder is genuinely uncomfortable when loaded, and there is far less organization than a pack. Totes also sag, which makes them harder to slide under a seat than a structured bag.
The one for airlines that publish no dimensions
Patagonia Black Hole Duffel 25L
Three major carriers publish no personal item figure, which means no number to fail against and no number to appeal to. A frameless duffel is the right answer to that ambiguity: nothing rigid for an agent to object to, and it compresses into whatever space actually exists - which varies between window and aisle seats more than people expect.
The specs that decide it
- Best for: Delta, Southwest and Alaska - the no-published-figure carriers
- Structure: Frameless, compresses to the available space
- Fabric: Coated and weather-resistant
Flaws but not dealbreakers
No structure means no organization - everything goes to the bottom and finding one item means unpacking several. There is also no laptop protection unless you add a sleeve.
The one that costs almost nothing and folds away
Narwey Foldable Travel Duffel Bag
If Basic Economy is occasional rather than routine, buying a dedicated under-seat bag is money spent on a problem you have three times a year. A foldable duffel lives flat inside your normal luggage and comes out for the flights that need it.
The specs that decide it
- Clears: Soft-sided - compresses into any carrier's under-seat space
- Storage: Folds flat when empty
- Cost: The cheapest solution to the personal item allowance
Flaws but not dealbreakers
Thin fabric, no structure, no padding. It will not survive being used as an everyday bag, and a full one is uncomfortable because the webbing handles dig into your hand.
How they compare
| Pick | Type | 18 x 14 x 8 | United 17 x 10 x 9 | Laptop protection |
|---|---|---|---|---|
| Cotopaxi Allpa 35L | Clamshell pack | Yes | No | Padded sleeve |
| Osprey Daylite Plus | Slim daypack | Yes | Yes | Basic sleeve |
| Baggallini Carryall | Structured tote | Yes | Check the model | Limited |
| Patagonia Black Hole 25L | Soft duffel | Yes | Compresses | None |
| Narwey foldable duffel | Foldable duffel | Yes | Compresses | None |
The limits, and the one that catches people
18 x 14 x 8 inches is the most common published US figure - American, Frontier and Spirit all use it. It has become the de facto manufacturing target, and a bag built to it passes on every carrier that publishes no dimension too.
The exception is United at 17 x 10 x 9. That 10-inch width is four inches under the common standard, and it is not something a firm push into a sizer solves. A large share of bags marketed as universal personal item bags fail it outright. JetBlue's 17 x 13 x 8 is also tighter than the standard, though less dramatically.
Under-seat space varies by seat
The space under a window seat is often narrower than under a middle or aisle seat because of entertainment and power boxes fitted to some aircraft. Bulkhead rows frequently have no under-seat space at all. If you are relying on a large personal item, do not book the bulkhead.
How we chose these picks
Fit against published dimensions first, because in this category that is the specification rather than a preference. Then access while the bag is under a seat, which rules out most top-loaders; whether it compresses, which is what saves you at a strict gate; and loaded weight, since you will be positioning this with your foot in a confined space.
We have not measured these against a gate sizer ourselves. The dimensions are manufacturers' stated figures checked against each airline's published limit - our methodology sets out what we verify and what we do not.
What we passed over
- Expandable personal item bags. The expansion takes them over the limit, on the exact fares where the limit is the whole allowance.
- Bags advertised as '18x14x8 universal'. That figure fails United's published limit on two dimensions, so it is not universal.
- Hard-sided under-seat cases. They cannot compress into the varying space under different seats and give up interior volume to the shell.
- Anything with protruding external bottle pockets. They count toward the measurement and they are what a sizer catches first.
How to choose a personal item bag
- Look up your airline's published figure. If there is one, that is the spec. If there is not, stay inside 18 x 14 x 8 and nothing will refuse you.
- If you fly United, check width first. Ten inches eliminates most of the category before anything else matters.
- Prefer clamshell or front access. These bags are used while they are under a seat, and top-loaders do not work there.
- Choose soft over rigid. Compression is your margin at a strict gate.
- Think about what actually needs to be reachable on the flight - see long-haul flight essentials.
Frequently asked questions
What is the best personal item bag size?
Will an 18x14x8 bag fit on United?
Can a tote be a personal item?
Does a personal item have a weight limit?
What should go in a personal item bag?
Read next
- Personal item size by airline
- Best underseat carry-on bags
- Long-haul flight essentials
- Best carry-on luggage
- TSA liquid rules
More in Luggage, or see every roundup and comparison on the site.