Airline Baggage Allowance Guide: Carry-On & Checked Limits
Airline baggage allowances are not standardized — carry-on size limits, personal-item rules, and checked-bag fees vary by airline and change often enough that a number you saw six months ago may already be wrong. The comparison below is built directly from each airline's own published baggage policy as of August 2026, but airlines update these policies with little notice, especially fees, so treat every figure here as a starting point and confirm the current rule on the airline's own website before you pack or pay for a bag. This guide covers the size and weight limits that actually get bags gate-checked or rejected at the counter — carry-on dimensions, personal-item dimensions, weight limits where they apply, and how the ultra-low-cost carriers differ from the legacy majors.
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Carry-On and Personal Item Limits by Airline
The four full-service US majors — American, Delta, United, and Alaska — plus JetBlue all use the same carry-on ceiling that's been the de facto US industry standard for years: 22 x 14 x 9 inches (56 x 36 x 23 cm), wheels and handles included, with no separate weight limit enforced domestically. Southwest uses a nearly identical box at 24 x 16 x 10 inches, and allows two free checked bags — the one meaningful allowance advantage left among the majors. The personal item — the bag that goes under the seat in front of you — is smaller and less consistently enforced at the gate than the carry-on, but every airline still defines a limit on paper, generally in the 18 x 14 x 8 inch range for the majors.
- American, Delta, United, Alaska, JetBlue: carry-on ≈22 x 14 x 9 in — no domestic weight limit enforced at the gate
- Southwest: carry-on ≈24 x 16 x 10 in, two free checked bags on every fare
- Spirit and Frontier: a full-size carry-on is a PAID add-on, not included even on the cheapest fare — only the personal item is free
- Personal item: roughly 18 x 14 x 8 in for the majors, though this dimension is checked far less consistently at the gate than the carry-on
- International carriers frequently enforce a carry-on WEIGHT limit (commonly 15-22 lb / 7-10 kg) that most US domestic carriers don't check — a bag that's fine on a US-based flight can get weighed and gate-checked on a codeshare international leg
Carry-on and personal-item limits, 8 US airlines (as of August 2026 — always verify on the airline's own site before flying)
| Airline | Carry-on (in) | Personal item (in) | Carry-on included free? |
|---|---|---|---|
| American Airlines | 22 x 14 x 9 | 18 x 14 x 8 | Yes, all fares |
| Delta Air Lines | 22 x 14 x 9 | 18 x 14 x 8 | Yes, all fares |
| United Airlines | 22 x 14 x 9 | 17 x 10 x 9 | Yes, all fares except Basic Economy on some routes |
| Alaska Airlines | 22 x 14 x 9 | 18 x 14 x 8 | Yes, all fares |
| JetBlue | 22 x 14 x 9 | 17 x 13 x 8 | Yes, all fares |
| Southwest Airlines | 24 x 16 x 10 | 18.5 x 13.5 x 8.5 | Yes, plus 2 free checked bags |
| Spirit Airlines | 22 x 18 x 10 (bin-sized bag) | 18 x 14 x 8 | No — carry-on is a paid add-on |
| Frontier Airlines | 24 x 16 x 10 | 18 x 14 x 8 | No — carry-on is a paid add-on |
Bottom line: If you're flying Spirit or Frontier, the personal item is your only free bag — plan to fit your trip into something that meets that smaller size or budget for the carry-on add-on at booking (it's cheaper in advance than at the gate).
Checked Bag Weight Limits and Fees
Weight is where checked bags get expensive fast. Every major US airline caps standard checked bags at 50 lb (23 kg); go even one pound over and the fee jumps to an overweight tier that's frequently double or more the standard checked-bag fee, and a bag over roughly 70 lb (32 kg) is often refused outright regardless of how much you're willing to pay. Fees themselves are the least stable number in this whole guide — they shift with fuel costs, competitive pressure, and fare-class promotions multiple times a year, so this guide intentionally does not quote exact dollar figures for each airline. Check the fee on the airline's own baggage page at booking, not from a search result or a blog post, since even airline-comparison sites lag real changes by weeks.
- Standard checked-bag weight ceiling: 50 lb (23 kg) on every major US carrier
- Overweight fee tiers typically start at 51 lb and again around 71 lb — the jump between tiers is usually steep enough that repacking to shed 2-3 lb pays for itself
- A bag over ~70 lb (32 kg) is refused outright by most carriers regardless of fee — airport baggage-handling equipment has its own safety limits
- Southwest's two free checked bags remain the biggest fee advantage among the majors for anyone checking a bag on every leg of a trip
- International long-haul itineraries sometimes carry a more generous checked allowance than the domestic leg of the same ticket — check the specific routing, not just the airline, since allowances can differ by cabin and alliance partner
How to Avoid Gate-Check and Overweight Fees
Gate-checking usually happens for one of two reasons: the flight is full and overhead bin space runs out before boarding finishes, or your bag is visibly over the carry-on size limit at the gate. Boarding earlier in your group reduces the first risk; a genuinely soft-sided bag that compresses slightly reduces the second, since gate agents eyeball bags against a sizer far more than they measure precisely. For checked bags, a luggage scale that costs under $15 pays for itself on the first overweight fee it prevents — weigh your bag at home before you leave, not for the first time at the counter.
- Board as early as your fare/status allows if bin space is a concern on a full flight
- A soft-sided carry-on that compresses slightly survives a borderline gate sizer better than a rigid hardshell at the exact limit
- Weigh checked bags at home with a cheap luggage scale before you leave for the airport
- If you're near the checked-bag weight limit, shift a few dense items (books, shoes) into your carry-on rather than pay an overweight fee
Frequently Asked Questions
What is the standard carry-on bag size for US airlines?
22 x 14 x 9 inches (56 x 36 x 23 cm), including wheels and handles, is the de facto standard across American, Delta, United, Alaska, and JetBlue. Southwest and Frontier allow a slightly larger 24 x 16 x 10 inch bag. There's no single legal standard — each airline sets its own limit, so a bag that clears one airline's sizer can be borderline on another's.
What is the personal item size limit?
Most US majors define a personal item as roughly 18 x 14 x 8 inches, though this varies more than carry-on limits do (United's is notably smaller at 17 x 10 x 9 inches) and gate agents check it far less consistently than the carry-on. A personal item has to fit under the seat in front of you, not just meet the airline's stated dimensions, so a bag that technically qualifies on paper can still be awkward on a full flight with a smaller seat-pitch aircraft.
Do Spirit and Frontier really charge for carry-on bags?
Yes — this is the single biggest allowance difference between the ultra-low-cost carriers and everyone else. On Spirit and Frontier, only the smaller personal item is free; a full-size carry-on is a paid add-on on every fare, and it's meaningfully cheaper to add it during booking than to pay at the airport counter or gate.
What happens if my checked bag is overweight?
You'll pay an overweight fee on top of the standard checked-bag fee, and most airlines apply it in tiers — commonly one tier starting around 51 lb and a steeper one around 71 lb. A bag over roughly 70 lb (32 kg) is often refused outright by ground crews regardless of fee, since airport baggage equipment has its own weight limits. Weighing your bag at home before you leave is the cheapest way to avoid this entirely.
Does Southwest still allow two free checked bags?
Yes, as of this guide's last check — it remains Southwest's signature baggage policy and the biggest fee advantage among the US majors for travelers checking a bag on every leg. Airlines do occasionally revisit long-standing policies like this, so if it's central to your trip's budget, confirm it's still current on Southwest's own site before you book.
Are international carry-on limits different from US domestic limits?
Often yes, in two ways: many international and regional carriers enforce an actual carry-on WEIGHT limit (commonly 15-22 lb / 7-10 kg) that most US domestic carriers don't check at all, and some international dimension limits run smaller than the US 22 x 14 x 9 inch standard. If your itinerary includes an international or codeshare leg, check that specific carrier's policy rather than assuming your outbound US airline's limits apply to the whole trip.
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