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Airline baggage guide
Personal Item Size by Airline in 2026: Dimensions and Limits
Your free personal item is the bag that slides under the seat in front of you, and every airline measures it differently. Compare personal-item dimensions for major U.S. carriers, check each measurement on your itinerary, and confirm under-seat fit on your aircraft.
Fast read
What matters first
Use this page as the practical filter before you open booking pages, maps, or official policy documents.
Best fit
Travelers comparing free under-seat bag limits before choosing or packing a bag.
Start here
A personal item is the smaller bag that fits under the seat in front of you. United permits 17 x 10 x 9 inches, but American and JetBlue permit only 8 inches on the smallest dimension. Compare all three measurements; no one airline sets the strictest limit on every axis.
Do not assume
An 18 x 14 x 8 inch bag can meet American’s size limit yet fail United’s 17 x 10 x 9 inch box. Compare every dimension across your operating airlines; Spirit’s former allowance is historical.
Decision system
The planning sequence
Use the sequence below to decide how this should shape the trip.
The under seat test
If it does not fit under the seat, it is not a personal item
Every airline defines the personal item the same way in practice: it has to slide fully into the space under the seat in front of you. Published inch limits are the airline stating how big that space is, and a gate agent can ask you to fit the bag into a sizer before boarding. United allows 17 x 10 x 9 inches, while American and Frontier allow 18 x 14 x 8 inches. The 9-inch bag can still fail an 8-inch limit. Spirit’s former allowance is historical; it ceased flying May 2, 2026. Delta lists no exact size and simply tests the under seat fit. The safe move when your trip mixes carriers is to pack to the smallest limit you will face, then keep the items you need in flight in that one bag.
Carry-on essentials
Move through the airport fast and keep everything in its place from gate to gate.
What counts as a personal item
Almost every major US airline gives you one free personal item in addition to a carry-on, and on the budget carriers the personal item is often the only free bag. It is the smaller piece that fits under the seat in front of you, such as a purse, a backpack, a laptop bag, or a small tote. The rule that matters is not the label on the bag but whether it slides fully into the under seat space. If it fits the size, count and fare rules, it qualifies for the free personal-item allowance. If it does not, the agent can move it to your carry-on allowance or charge a fee.
Personal item size by airline
Overhead bag instead? See the companion carry-on size chart by airline. Quick chart first. This chart was originally described as checked July 2026. Current policy qualifications below were reviewed October 3, 2026. The rows are not a universal strictest-to-largest ranking, and unconfirmed figures are labeled. The notes below the chart cover enforcement and real-world fit.
| Airline | Personal item (in) | Personal item (cm) | Notes |
|---|---|---|---|
| United Airlines | 17 x 10 x 9 | 43 x 25 x 22 | Compare every dimension; a 9-inch-thick bag does not meet an 8-inch limit |
| JetBlue | 17 x 13 x 8 | 43 x 33 x 20 | Must slide fully under the seat |
| Breeze Airways | 17 x 13 x 8 | 43 x 33 x 20 | Published limit, no weight cap |
| Avelo Airlines | 17 x 13 x 9 | 43 x 33 x 22 | Included free with every fare |
| American Airlines | 18 x 14 x 8 | 45 x 35 x 20 | Purse, backpack, or laptop bag that fits under the seat |
| Delta Air Lines | 18 x 14 x 8 (unconfirmed example) | 45 x 35 x 20 (unconfirmed example) | One free personal item; Delta’s linked policy requires under-seat fit. These example dimensions are not a confirmed Delta maximum. |
| Spirit Airlines (historical) | 18 x 14 x 8 | 45 x 35 x 20 | Former allowance only; Spirit ceased flying on May 2, 2026 |
| Frontier Airlines | 18 x 14 x 8 | 45 x 35 x 20 | Measured including handles and wheels |
| Allegiant Air | 18 x 14 x 8 | 45 x 35 x 20 | Free personal item on every fare |
| Sun Country | 17 x 13 x 9 | Approx. 43 x 33 x 23 | Free personal item; official maximum is 17 x 13 x 9 inches and under-seat fit is required |
| Southwest Airlines | 18.5 x 8.5 x 13.5 (unconfirmed example) | 47 x 22 x 34 (unconfirmed example) | Current rule requires under-seat fit. The listed example is not confirmed for every Southwest aircraft. |
| Alaska Airlines | No published size | Fits under the seat | No numeric limit; under-seat fit is the test |
| Hawaiian Airlines | No published size | Fits under the seat | Purse, laptop bag, or backpack that fits under the seat |
Airlines change limits without much notice. If a bag is borderline for your dates, re-check the airline’s official baggage page before you fly.
American and Frontier publish 18 x 14 x 8 inches; Spirit’s matching former allowance is historical. United’s 17 x 10 x 9 inches and JetBlue’s 17 x 13 x 8 inches constrain different axes. Southwest’s under-seat fit rule should control your packing; the 18.5 x 8.5 x 13.5 inches listed here is not confirmed for every aircraft. Delta is the outlier that publishes no exact figure and tests the under seat fit instead. Frontier states its limit as 14 inches tall, 18 inches wide, and 8 inches deep, and counts handles, wheels, and straps in that total.
The bag that fits almost every airline
If you fly one airline, check its dimensions and your aircraft’s under-seat space. For mixed carriers, compare each axis separately. For example, 17 x 10 x 8 inches fits within the published dimension boxes for United, American and JetBlue, but this is a calculated comparison, not a guarantee for every airline, seat or packed bag. United’s full 17 x 10 x 9 inch allowance does not meet their 8-inch thickness limits.
Why gate agents check more closely now
Budget carriers have tightened personal item enforcement because the personal item is the free bag and the carry-on is the paid one. Frontier uses a personal-item sizer, and an oversized bag can incur a gate bag charge. Spirit’s former gate policies are historical because it ceased flying May 2, 2026. The lesson is to measure honestly at home, including the handles and wheels, rather than trusting that a bag sold as airline legal will actually pass. A soft bag overstuffed past its seams is the most common bag that looks fine on the floor and fails at the sizer.
Personal item versus carry-on
Keep the two bags straight, because they have separate rules. The personal item is the small bag under the seat, free on every major airline. The carry-on is the larger roller or duffel that goes in the overhead bin, included with many legacy fares but separately charged on Frontier and some Basic fares; Spirit’s former fees are historical. When the bins fill or the fare is the cheapest tier, the carry-on is the bag at risk of a gate check, so the personal item is where you keep anything fragile, valuable, or needed in flight.
Planning traps
Mistakes to avoid
These are the small decisions that quietly derail an otherwise good plan.
Measuring the bag body only. The published limits include handles, wheels, and straps, so a bag that looks legal can still fail the sizer.
Assuming one size fits every airline. A 18 x 14 x 8 inch bag is fine on American but too tall for United, which permits 17 x 10 x 9 inches; compare each axis in the airline’s stated orientation.
Treating Delta's silence as no limit. Delta publishes no figure, but the under seat space still binds, so an oversized bag is still refused.
Overstuffing a soft bag. A bag packed past its seams will not slide under the seat even when its empty dimensions are within the limit.
Sources checked
Official and supporting references
Spirit ceased flying on May 2, 2026; its dimensions here are historical. See Spirit’s official shutdown announcement.
Use these links to verify live prices, dates, rules, and operating details before money changes hands.
FAQ
Common planning questions
What is the standard personal item size?
Which airline has the smallest personal item size?
What size personal item fits all airlines?
Does Delta have a personal item size limit?
Can a backpack be a personal item?
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