Carry-On vs Personal Item: Size Limits, Packing Differences & What Fits

US airline size limits compared

The following dimensions are the published limits as of 2026. All are linear inches (length + width + depth combined) unless otherwise noted. Always verify on the airline's website before travel, as policies change.

• American Airlines: carry-on 22×14×9 in (56×36×23 cm); personal item fits under the seat.
• Delta Air Lines: carry-on 22×14×9 in (56×36×23 cm); personal item 18×14×8 in (46×36×20 cm).
• United Airlines: carry-on 22×14×9 in (56×36×23 cm); personal item 17×10×9 in (43×25×23 cm).
• Southwest Airlines: carry-on 24×16×10 in (61×41×25 cm); no checked bag fee for first two bags.
• Spirit Airlines: carry-on max 22×18×10 in (56×46×25 cm); personal item 18×14×8 in (46×36×20 cm). Carry-on fees apply — personal item is always free.
• Frontier Airlines: carry-on 24×16×10 in (61×41×25 cm); personal item 18×14×8 in (46×36×20 cm). Carry-on fees apply on basic fares.
• JetBlue: carry-on 22×14×9 in (56×36×23 cm); personal item 17×13×8 in (43×33×20 cm).

How airlines actually measure bags

Most airlines use a carry-on sizer box at the gate — a metal frame matching the maximum dimensions. If your bag fits in the frame with handles and wheels compressed, it passes. Soft-sided bags flex slightly and often pass even if technically oversized; hard-sided bags that exceed the limit will fail.

Gate agents enforce strictly on full flights, especially at budget carriers. If overhead space is full, agents begin gate-checking bags — even bags that meet size requirements. Gate-checking is free but means waiting at baggage claim.

In practice, most major airlines do not proactively measure carry-ons unless the bin is obviously full or the bag is clearly oversized. Budget carriers (Spirit, Frontier, Allegiant) are more aggressive because carry-on fees are a revenue line.

What fits in a personal item

A personal item at 18×14×8 in accommodates more than most travelers expect. Typical contents that fit: a 13-inch laptop with sleeve, a change of clothes, toiletries bag, chargers and cables, headphones, a book, and a small jacket.

Bags designed specifically as personal items include: 20–25L daypacks that compress to under the seat, women's large totes (many sit at exactly 17×13 in), slim laptop bags, and camera bags under 20L.

What does not fit: full hiking daypacks (30L+), full-size camera bags, standard backpacks without compression, and anything that creates a rigid shape too wide for the under-seat space.

What fits in a carry-on

• A week of clothes with efficient packing (packing cubes, rolled garments): achievable in 40L.
• A laptop and accessories: standard in any carry-on side pocket.
• Toiletries: TSA 3-1-1 bag fits all liquids (3.4oz / 100ml containers, 1 quart bag).
• Shoes: one extra pair adds significant volume — roll them in a bag and pack around them.
• What cannot go in carry-on: liquids over 3.4oz, razor blades, tools over 7 inches, firearms, and anything flagged by TSA security. Full TSA prohibited items list at tsa.gov.

One-bag travel: carry-on only vs carry-on plus personal item

Traveling with only a carry-on (no personal item) leaves maximum overhead bin space for your bag. On a full flight this matters — overhead bins fill from front to back, and late boarding means your carry-on may get gate-checked.

Using both allowances (carry-on + personal item) gives you the most total volume without checking a bag. The personal item goes under the seat in front of you, reducing your leg room slightly but keeping both bags in the cabin.

For trips under 5 days: a single 30–40L carry-on or a personal item plus a small carry-on handles most wardrobes. For 7–14 days: carry-on plus personal item is the efficient maximum before a checked bag becomes necessary.