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Compare 12 US airlines

Personal item size by airline

US personal-item rules are not one size. When airlines publish inches, the common boxes are 18 × 14 × 8 (American, Frontier; Allegiant publishes the same box as 8 × 14 × 18), 17 × 13 × 8 (JetBlue, Breeze), 17 × 13 × 9 (Sun Country, Avelo), and United’s stricter 9 × 10 × 17. Four major carriers (Delta, Southwest, Alaska, Hawaiian) only require the item to fit under the seat and do not publish exact dimensions. The strictest published width is United’s 10 in. Personal items are typically free on all 12 airlines on this page (including budget airline base fares). Measure the bag when packed, including wheels, pockets, and straps.

TL;DR

  • Personal items are typically free on all 12 airlines on this page (including budget airline base fares) when they fit the published box or under the seat.
  • Published boxes: American and Frontier 18 × 14 × 8; Allegiant 8 × 14 × 18 (same box, different axis order); JetBlue and Breeze 17 × 13 × 8; Sun Country and Avelo 17 × 13 × 9; United 9 × 10 × 17 (strictest published width is 10 in).
  • Delta, Southwest, Alaska, Hawaiian: under the seat only (inches not published). American or United sizes don’t apply to those airlines.
  • United Basic Economy (most domestic): the personal item is usually the only free cabin bag; fail under-seat fit and you may face a paid check (about $75 at the gate for tickets bought on or after April 3, 2026).
  • Measure packed, including wheels, pockets, and straps (bag sizer guide). Open your airline’s page below.

At the airport (quick)

  1. Know if a personal item is your whole cabin allowance. That is common on United Basic Economy and many budget airline base fares (Basic Economy guide).
  2. Measure the packed bag for under-seat fit. United’s 10 in width is where soft bags most often fail; airlines without published inches still need a real under-seat bag (bag sizer).
  3. If it won’t fit, expect it to be treated as a carry-on or checked bag. Pay earlier when fees apply (when to pay). Regional personal-only jets: regional jet guide.

Each airline’s personal item page has full dimensions, an FAQ, and its Last verified date.

Also: Carry-on size · Baggage fees · United personal item

Figures come from each airline's official pages. Check them before you fly.

Each airline row links to our page for that airline, with official sources and a last-verified date. How we check: /about/.

Good to know

  • Delta, Southwest, Alaska, and Hawaiian: under the seat only, with no published inches. American, United and Frontier sizes don’t apply to these airlines.
  • United Basic Economy (most domestic): the personal item is usually the only free cabin bag; fail under-seat fit and it’s $75 at the gate (tickets bought on or after April 3, 2026).
  • Allegiant axis order: Personal 8 × 14 × 18 (not reordered as Frontier’s 18×14×8).
  • Wheels, handles, and straps count when the airline says its exterior dimensions include them (Frontier, Allegiant, and others).

Examples sized to published boxes

Examples sized to common published boxes. Measure when packed; these are not a claim that one bag fits every airline.

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Airline pages

Related

FAQ

What is a personal item on US airlines?
A smaller bag that must fit under the seat in front of you (purse, small backpack, laptop bag or similar item). It is separate from the overhead carry-on. Exact inches exist only when the airline publishes them.
Which US airlines do not publish personal-item dimensions?
Delta, Southwest, Alaska, and Hawaiian require under-seat fit and list examples only; they do not publish exact dimensions. For these four, go by under-seat fit, not a set of inches.
What is the strictest published personal-item size?
United at 9 × 10 × 17 inches (22 × 25 × 43 cm). The 10 in width is where most bags fail. Soft bags should measure 10 in wide or less when packed.
Is a personal item free on Basic Economy or budget airline base fares?
Yes on all 12 airlines on this page, for a personal item that meets the size limit. The catch differs: United Basic Economy often allows only the personal item onboard; Frontier, Allegiant, Sun Country, Avelo, and Breeze No Flex charge for a full overhead bag.
What if my personal item does not fit under the seat?
Expect it to be treated as a carry-on or checked bag. On United Basic Economy, that often means a $75 gate fee for tickets purchased on or after April 3, 2026. On Frontier and Allegiant, oversized personal items can trigger carry-on or airport fees (prices vary or follow published ranges; check the airline’s site).
What size should I shop for if I fly multiple airlines?
Soft bags about 17 × 13 × 8 or smaller on the outside when packed fit JetBlue and Breeze and stay under American and Frontier’s 18 × 14 × 8. For United (especially Basic Economy), aim for 9 × 10 × 17 or smaller. Always measure packed; airport sizers are rigid.

Disclaimer

Bag rules change. Confirm size, fee, and fare rules on the airline site before you travel. BagRule is a publisher site and does not sell tickets or bags.