Personal Item Bag Size: Under-Seat Rules by Airline

A personal item is the bag that has to sit under the seat in front of you. It is not the overhead carry-on. On a standard mainline fare you usually get both. On United Basic Economy, Frontier, Allegiant, and a Ryanair or Vueling Light fare, this bag is often the only one that boards free.

Purses, laptop sleeves, briefcases, small backpacks, and slings all count if they fit the published box, or if they actually go under the seat on carriers that publish no inches. A garment bag is the carry-on slot, not this one. That split is on do garment bags count as carry-on.

There is no single “standard” under-seat box. American and Frontier share 18 x 14 x 8. United does not. JetBlue does not. Delta and Southwest do not publish inches at all. Copying 18 x 14 x 8 onto those five carriers is how most roundups, including an older version of our backpack page, get the table wrong.

The six rows below are the cluster we keep in static HTML. Last-checked dates are the day we stored the carrier page, not a sizer session. We have not taped these bags into a United or JetBlue gauge for this restore. Measure your packed bag against the row for the ticket you bought. Method: how we measure and how to measure luggage.

Vueling matches Ryanair at 40 x 30 x 20 cm. Fly Light is that bag only. Fly, Fly Grande, Fly Pro, Premium, and infants also get a 10 kg 55 x 40 x 20 cm overhead bag. Gate: 60 to 75 EUR if the under-seat bag breaks 40 x 30 x 20 cm, 110 to 140 EUR if any piece breaks 55 x 40 x 20 cm. Source, read 5 September 2026: Vueling hand-luggage help.

easyJet’s free under-seat bag is 45 x 36 x 20 cm in our 21 August 2026 stored row. easyjet.com 403’d a direct fetch on 5 September 2026, so that figure is not a same-day reread. It is the generous European personal item next to Ryanair’s 40 x 30 x 20 cm. Source URL in the dataset: easyJet cabin bags.

United’s carry-on page writes the personal item as 9 x 10 x 17 inches (22 x 25 x 43 cm). Same box as 17 x 10 x 9, height last. A bag listed at 18 x 14 x 8 is 1 inch too tall and 4 inches too wide for that under-seat limit. Do not buy an “airline personal item” pack for United because the Amazon title says 18 x 14 x 8.

On most domestic United flights, Basic Economy is this bag only. The overhead carry-on comes back on fares to South America and on transatlantic and transpacific sectors. CommutAir regionals are personal item only on every fare, not only Basic Economy. Direct fetches of united.com often 403; the 9 x 10 x 17 wording is from United’s public carry-on page as it still appeared in search on 5 September 2026.

American is the US major that publishes 18 x 14 x 8 inches (45 x 35 x 20 cm) for the personal item. That is also Frontier’s box, which is why so many backpacks are cut to it. It is not United’s box and it is not JetBlue’s box. Handles, wheels, and external pockets count.

American Basic Economy still includes the carry-on plus the personal item, the opposite of United. The overhead number is 22 x 14 x 9, including handles and wheels. That overhead rule is not this page. Soft-sided garment bags have a separate 51-inch / 130 cm total on American; that is the carry-on, not a third item, and it lives on the garment-bag slot page.

JetBlue’s help page, read 5 September 2026, says personal items must not exceed 17 inches long, 13 inches wide, and 8 inches high, including wheels and handles. The 8-inch height is the shallow number. A pack that clears American’s 8-inch depth can still miss JetBlue on length or width.

Blue Basic still includes one carry-on and one personal item. JetBlue does not publish a carry-on weight cap. There are no garment-bag closets on JetBlue aircraft.

Delta’s carry-on page, read 5 September 2026, allows one carry-on and one personal item on every fare, including Main Basic. Approved personal items are a purse, briefcase, small backpack, belt bag, camera bag, diaper bag, laptop bag, or something of similar size that fits under the seat. There are no personal-item inches on that page. Inventing 18 x 14 x 8 for Delta is a roundup habit, not a Delta rule.

Delta Connection flights with 50 seats or fewer take personal items only. Rollers get a pink planeside tag. The overhead carry-on, when it is allowed, is 22 x 14 x 9 including handles and wheels, or 45 linear inches. That is the bin bag, not this one.

Southwest publishes 24 x 16 x 10 for the carry-on, wheels and handles in, and does not publish personal-item inches. The help article names a purse, briefcase, laptop case, or backpack and says it goes under the seat. A bag that clears Southwest’s carry-on box will not clear American, Delta, United, or JetBlue in the bin. Carry-on detail: Southwest airline carry-on size.

Frontier’s free bag on every fare is the personal item, listed 18 x 14 x 8 including handles, wheels, and straps. The carry-on is paid unless it is in a bundle. Frontier’s own page says personal-item size is checked at boarding. Stored 21 August 2026 from Frontier bag options.

Allegiant publishes the same box as 8 x 14 x 18 inches, written smallest side first. Reordered, that is 18 x 14 x 8. Wheels, pockets, handles, and decorations count. A personal item that does not sit entirely under the seat is reclassified and charged as a carry-on. Stored 21 August 2026 from Allegiant baggage.

Spirit is gone. It began an orderly wind-down on 2 May 2026 and cancelled its flights. The 18 x 14 x 8 box it used to publish is not a live rule.

Take the tape to the bag as you will fly it, stuffed. Height, width, and depth include wheels, handles, bottle pockets, and the bulge of a stuffed front organizer. Airlines measure the outside. A product page that says “body only” is not the sizer number.

If your ticket is United, start with 17 x 10 x 9, not 18 x 14 x 8. If it is JetBlue, start with 17 x 13 x 8. If it is American or Frontier, 18 x 14 x 8 is the published box. If it is Delta or Southwest, there is no published box; the test is whether the packed bag goes under the seat on that aircraft. Tape method: how to measure luggage. Scale drawing: luggage size visualizer.