Carry-on size limits are set by the airline, not by law, and they vary

The Transportation Security Administration (TSA) does not enforce a single carry-on size limit. Instead, each airline sets its own rules for what fits in the overhead bin or under the seat in front of you. Most major U.S. carriers allow a bag that is roughly 22 inches long, 14 inches wide, and 9 inches deep, but some airlines are stricter, and budget carriers often charge extra if your bag exceeds their limit.

Before you pack, check your airline's website for their specific dimensions. The airline you are flying with is the only one whose rules matter for your trip. If you are flying multiple airlines on a connecting flight, you need to meet the strictest requirement among them.

Key Takeaways

  • Most major airlines allow carry-on bags up to 22 x 14 x 9 inches, but budget carriers and some international airlines have smaller limits.
  • Airlines measure length, width, and depth including wheels and handles, so a bag that fits the dimensions on paper may not fit in practice.
  • If your bag is too large, the airline will gate-check it (send it to baggage claim) at no charge, but you lose access to it during the flight.
  • Soft-sided bags compress slightly and may pass inspection when a hard-sided bag of the same dimensions would not.
  • Your airline's website or customer service line is the only reliable source for their current carry-on policy.

Standard carry-on dimensions for major U.S. airlines

The most common limit among full-service carriers is 22 x 14 x 9 inches (56 x 36 x 23 centimeters). This includes wheels and handles. Airlines that follow this standard include American, Delta, United, and Southwest. Alaska Airlines allows the same size.

Budget carriers are often stricter. Frontier and Spirit Airlines limit carry-on bags to 22 x 18 x 10 inches, which sounds larger but is actually smaller when you account for the depth. Allegiant Air allows 22 x 14 x 9 inches but charges a fee if your bag does not fit their sizer (a metal frame at the gate). JetBlue allows 22 x 14 x 8 inches, which is one inch shallower than the standard.

International airlines vary widely. If you are flying to or from another country, check that airline's rules separately. Some European carriers allow smaller bags, and some Asian carriers allow larger ones.

How airlines measure your bag at the gate

Airlines do not weigh carry-on bags or measure them before you board. Instead, gate agents use a visual check or a metal sizer frame. If your bag fits in the frame without being forced, it passes. If it does not, the agent will gate-check it—send it to baggage claim—at no charge.

This is where soft-sided bags have an advantage. A soft duffel or rolling bag compresses slightly when placed in the sizer, while a hard-sided suitcase does not. A soft bag that is technically one inch too wide may still pass inspection, while a hard bag of the same dimensions will not. This is not a may provide, and it depends on the agent's judgment.

Wheels and handles count toward the dimensions. A bag that is 22 inches long with the handle extended is 22 inches long, even though the handle is not part of the bag itself. Measure your bag with the handle fully extended and the wheels down.

What happens if your bag is too large

If your carry-on is too large, the airline will gate-check it for free. This means your bag goes into the cargo hold with checked luggage and arrives at baggage claim when you land. You cannot access it during the flight, and you cannot use it to store items you want to keep with you.

Gate-checking is not a fine or a penalty—it is a standard procedure. It happens most often on full flights when the overhead bins are full, even if your bag technically meets the size limit. If you are worried about losing access to your bag, pack a smaller personal item (a purse, backpack, or laptop bag) that fits under the seat in front of you.

Personal items and the two-bag rule

Most airlines allow you to bring both a carry-on bag and a personal item at no charge. The personal item is usually smaller—a purse, laptop bag, or small backpack. It must fit under the seat in front of you, not in the overhead bin.

The TSA does not limit the size of a personal item, but your airline does. Most carriers define a personal item as something that fits in a space roughly 18 x 14 x 8 inches, though they do not always enforce this strictly. If you are unsure whether your bag counts as a personal item or a carry-on, ask the airline before you travel.

Budget airlines sometimes charge for a carry-on bag if you do not also buy a checked bag. Frontier, for example, includes a personal item free but charges for a carry-on unless you purchase a higher fare class or a checked bag. Read the fine print on your airline's website.

Tips for packing within the carry-on limit

Measure your bag before you buy it. Most luggage retailers list the dimensions in the product description. If you are buying in a store, bring a tape measure or ask the staff to measure it for you. Remember to measure with the handle extended and wheels down.

Roll your clothes instead of folding them to save space. Use packing cubes to compress clothing and organize items by category. Wear your bulkiest items (jacket, boots) on the plane instead of packing them. Fill shoes with socks or small items to use the space inside them.

Keep liquids, gels, and aerosols in a clear plastic bag no larger than one quart (roughly 7 x 8 inches). This is a TSA rule, not an airline rule, and it applies to all flights in the United States. Each container must be 3.4 ounces (100 milliliters) or smaller. Pack this bag where you can reach it easily at security.

Frequently Asked Questions

Can I bring a roller bag and a backpack on the plane?

Yes, if the backpack counts as your personal item and the roller bag is your carry-on. The personal item must fit under the seat in front of you. If both bags are large, the airline may ask you to check one of them.

What if I am flying with a connecting flight on a different airline?

Your carry-on must meet the size limit of the strictest airline on your itinerary. If you fly American to Denver and then Southwest to Los Angeles, and both airlines have the same limit, you are fine. If one airline is stricter, follow that limit for the entire trip.

Do I need to remove my carry-on at security?

Yes. At the TSA checkpoint, place your carry-on bag on the conveyor belt so it can go through the X-ray machine. You will pick it up after security. This is separate from the size check at the gate.

Can I bring a car seat or stroller as a carry-on?

Car seats and strollers are usually not counted as carry-on bags. Most airlines allow you to gate-check them for free if you do not need them during the flight. If you need the car seat on the plane, you can bring it as a carry-on in addition to your regular bag. Ask your airline before you travel.

What if my bag is one inch too big?

It depends on the agent and the airline. Some agents measure strictly; others use visual judgment. A soft-sided bag that is slightly oversized may pass, while a hard-sided bag will not. If you are close to the limit, arrive early so you have time to check with the airline before boarding.