Personal Item Size by Airline: The Under-Seat Limit

• 17x13x8 in

  JetBlue's published personal-item limit

• Under seat

  Where a personal item goes, separate from the carry-on overhead

• 1 per person

  A personal item is the smaller of the two cabin-item types

• 22x14x9 in

  Carry-on reference; the personal item is the smaller of the two

A “personal item” is the smaller bag carried at your feet, and it is the only allowance that survives a basic economy fare on several carriers. Yet there is no national personal-item size. Each airline writes its own rule, and the rule is often described as a fit rather than a number, which makes it easier to get wrong. This guide records only what each carrier states, without inventing a dimension it did not publish.

The scope here is narrow on purpose. The carry-on size guide covers the larger overhead bag; this page answers the separate under-seat question. Where an airline publishes a personal-item dimension, you get the number. Where it does not, you get the exact fit language and a way to confirm before you pack. Neither this page nor any other can replace the airline’s own current baggage page for the flight you booked.

What a personal item is and why size matters

The two-bag model is standard across most U.S. carriers: one personal item and one carry-on. The personal item is the one that must fit under the seat, and the carry-on goes in the overhead bin. On a basic economy fare the carry-on can disappear, leaving the personal item as your only free bag, which is why sizing it correctly matters more than people expect.

The size rule is separate from the contents rule. TSA decides what you may carry through the checkpoint, such as liquids over 3.4 ounces, while the airline decides what fits under the seat. A bag can be small enough and still be turned aside for its contents, or correctly packed and oversized for the seat space. Confirm both before you travel, and note that TSA’s guidance directs travelers to the airline for size questions.

JetBlue: a published 17 by 13 by 8 inches

JetBlue publishes an exact personal-item limit: 17" L x 13" W x 8" H. That is the rare airline that states a number for the under-seat bag, and it is useful precisely because many carriers do not. JetBlue’s carry-on page describes one personal item per customer, and its stated personal-item dimension is a published, verifiable figure reviewable on its official page.

JetBlue also states there is no current carry-on weight limit, only that you be able to lift the bag. That explicit statement is worth keeping separate from the personal-item size, because weight and dimensions are different limits. A bag can be light and still too large for the personal-item dimension, or fit the size and exceed a weight rule on another carrier that does publish one.

If your itinerary combines JetBlue with another carrier, use the stricter of the two personal-item rules for the connecting flight, because the operating carrier sets the practical size at boarding. A dimension that suits JetBlue can exceed the under-seat fit a partner or code-share airline describes.

When carriers describe a fit instead of inches

Several major carriers describe the personal item as one that fits under the seat without publishing inches. Frontier is an important exception: it includes one personal item with every ticket, capped at 18" x 14" x 8" and 35 pounds, including handles, wheels and straps. Delta’s page names a personal item as a bag of a type that fits under the seat, without stating a universal number. Southwest’s policy describes the personal item as a smaller item that fits under the seat or in the overhead compartment, again without a single published dimension.

This guide does not invent a number for those carriers. Where the live page does not state a personal-item dimension, the honest answer is that the airline uses an under-seat fit test rather than a fixed size. That is a real difference from JetBlue, and it means the practical limit is decided by the seating and staff judgment on your flight rather than a single inch value.

The written limit vs the on-day enforcement

The written personal-item rule and the way an airline enforces it at the gate are two different things. Some carriers check a published dimension against the bag; others rely on a staff fit test under the seat or in a sizer. A bag that meets the number on the page can still be asked for a different arrangement when the space is tight or the flight is full.

This distinction matters for packing. Leave a margin rather than buying or packing a bag that sits exactly at a limit, because enforcement can include the extended handle, the wheels and a soft-sided bulge. Measure the packed bag, not the empty one, and keep it comfortably under any published dimension rather than scraping it.

On a full flight an airline can also move a qualifying personal item to a different stowage or, where it is the carry-on rather than the personal-item bag, gate-check it. The personal item is the one most often kept at your feet, but nothing is guaranteed when space is short. Keep the essentials in it that you need during the flight, in case the carrier asks it to be handled differently at boarding.

Wheels, handles, pet carriers and packed bulk

Where the airline says wheels, handles and straps are included, the published dimension is the maximum of the entire physical bag. Frontier is explicit about including those parts in its personal-item limit. Measure the bag fully packed, because the dimensions on a manufacturer label may not reflect a bulging pocket or protruding hardware.

Pet carriers are a separate question from the ordinary personal item. Some airlines count a small pet carrier in the cabin as your personal item, while others treat it separately or as an additional carrier fee. If you travel with a pet, the pets-in-cabin guide covers that policy; on this page, the point is that a pet carrier is not automatically a free spare bag on top of your allowance.

Soft-sided bags bulge when overstuffed, and a dimension measured at the factory changes when you fill it. Choose a personal item with room to spare under the strictest limit on your itinerary, and expect the packed and handle-extended measure to be larger than the label. That margin is the difference between a smooth boarding and a fee.

Basic economy, fare type and partner carriers

Fare type changes whether the personal item is your only bag or one of two. On basic economy fares from several carriers the free allowance is a personal item only, with a carry-on charged or restricted. The basic economy comparison details when that trade-off is worth it; the personal-item distinction here is that on those fares the under-seat bag is your whole allowance, so its size is the deciding factor in what can come free.

A connecting itinerary can span more than one operating carrier, and each can set its own personal-item rule. A bag that fits the first airline can exceed the advertised limit on the second, especially when one carrier publishes inches and the other describes a fit. Treat the standard of the operating carrier on each leg as the rule that applies there.

When a site you read gives a generic “standard personal item size,” compare it against the airline’s current baggage page before trusting the search result. A fare page or third-party blog can lag the current limit. The official page is the number staff are trained to apply, and it is worth the extra minute to confirm it for your exact booking.

Personal-item limits at a glance

Read the table right to left. The count tells you how many personal items and how they are allowed; the dimension tells you whether a number is published or a fit is required. Frontier includes one qualifying personal item with every ticket, but an oversized bag is subject to the airline’s current charge, so measure the packed bag before departure.

Where a carrier does not publish a dimension, the honest and useful answer is that the airline uses an under-seat fit. Do not take a number from another airline and apply it to one that never published it. Confirm the fit for the carrier you booked, and contact the airline if the exact case is not stated before you pay.

A pre-trip personal-item checklist

1. Name the carrier on each leg. List every operating airline on the itinerary, not just the first.
2. Open each carrier’s personal-item rule. Note whether it publishes inches or requires an under-seat fit.
3. Check the fare. Note whether basic economy makes the personal item your only free bag.
4. Pack and measure the bag. Extend the handle, fill it, and keep it under the strictest number or fit on the itinerary.
5. Confirm contents with TSA. Verify liquids and any restricted items on the current TSA list.
6. Recheck before departure. Personal-item rules are current as of 12 August 2026; confirm the airline page again close to travel.

The rule that survives every airline change is to match the carrier you actually booked. Some carriers publish a personal-item dimension and others describe an under-seat fit, and the difference is real. Measure the packed bag against the published number, leave a small margin for the handle and packed bulk, and keep the essentials at your feet so a full-flight change does not leave you reaching for a bag that moved. Personal-item size is a set of specific carrier rules, not one national number, and confirming yours is the fastest way to board without a fee.