Southwest's carry-on dimensions and what you can bring aboard

Southwest Airlines allows one free carry-on bag and one personal item on every flight. Your carry-on bag can be no larger than 24 inches long, 16 inches wide, and 10 inches deep. That's measured at the widest points of the bag itself, not including wheels, handles, or pockets that stick out.

The personal item — a purse, backpack, laptop bag, or small daypack — must fit under the seat in front of you. Southwest doesn't publish exact dimensions for personal items, but the rule is straightforward: if it fits under the seat without blocking the aisle or your own legroom, it counts. Most standard purses, small backpacks, and laptop bags pass without question.

Southwest does not weigh carry-on bags at the gate. Weight limits exist for checked bags (50 pounds per bag), but carry-on bags can be as heavy as you can lift into the overhead bin yourself. If a bag is too large to fit in the overhead compartment or under a seat, a gate agent will ask you to check it at no charge — that's part of Southwest's checked-bag policy.

Key Takeaways

  • Carry-on bags must not exceed 24 inches long, 16 inches wide, and 10 inches deep, measured at the bag's widest points.
  • You get one free carry-on bag plus one personal item that fits under the seat in front of you.
  • Southwest does not weigh carry-on bags, so size is the only limit that matters at the gate.
  • If your bag is too large for the overhead bin, a gate agent will check it for free rather than charging a fee.
  • Wheels, handles, and expandable pockets do not count toward the 24-by-16-by-10 measurement.

How to measure your bag correctly

The measurement matters because gate agents use a sizing frame — a metal or plastic box with the exact dimensions — to check bags that look close to the limit. You can measure your own bag at home with a tape measure or ruler. Measure the length (top to bottom), width (side to side), and depth (front to back) at the widest point of each dimension. If your bag is 24 by 16 by 10 or smaller, it will pass.

Many rolling carry-on bags sold as "carry-on compliant" are built to fit these dimensions. If you buy a bag labeled as Southwest-compliant or carry-on-sized, you're safe. If you're unsure about a bag you already own, measure it before you pack for your trip. A bag that's 25 inches long will not fit, even by one inch.

What happens if your bag is too large

If your carry-on bag is larger than 24 by 16 by 10 inches, a gate agent will ask you to check it. This happens at the gate, not at the ticket counter, so you won't know until you're boarding. Southwest will check the bag for free — you won't pay a fee — but your bag will arrive at baggage claim instead of traveling with you on the plane.

If you're traveling with a tight connection or need your bag during the flight, this creates a real problem. The best approach is to measure your bag before you leave home. If it's borderline, pack lighter or use a smaller bag. Rolling bags that are slightly undersized are inexpensive and save the hassle of gate-checking.

Personal items and what counts as one

Your personal item is separate from your carry-on bag. Common personal items include a purse, small backpack, laptop bag, camera bag, or small daypack. The rule is that it must fit under the seat in front of you without blocking the aisle or your legroom. You won't be turned away for having a personal item that's slightly larger than average, as long as it physically fits under the seat.

A full-size rolling suitcase does not count as a personal item — that's a carry-on bag and takes up your one free carry-on allowance. A large hiking backpack might also be considered a carry-on bag rather than a personal item if it's too big to fit under a seat. When in doubt, ask at the ticket counter before you board.

Bags that often cause problems at the gate

Soft-sided duffel bags and expandable rolling bags are the most common culprits. A duffel bag that measures 25 inches when packed might compress to 23 inches when you squeeze it, but Southwest measures the bag itself, not how full it is. If the bag's maximum dimensions exceed the limit, it will be checked. Expandable bags with zippers that let you add depth are measured in their expanded state, not their compressed state.

Backpacks with external pockets, straps, and compression cords also cause confusion. The measurement is the bag itself, not the stuff hanging off it. A backpack that's 24 inches tall, 16 inches wide, and 10 inches deep at its widest point is fine, even if it has pockets or straps that extend beyond those dimensions.

Overhead bin space and when bags get checked

Even if your bag meets the size requirement, it might not fit in the overhead bin on a full flight. Overhead bins fill up quickly, especially on popular routes or afternoon flights. If the bin is full when you board, a gate agent will check your bag at no charge. This is not a penalty — it's how Southwest manages space on crowded planes.

If you're on a flight that's likely to be full, arrive early to board in an earlier group. Southwest uses open seating, and earlier boarding groups get first pick of overhead bin space. You can also choose to gate-check your bag voluntarily if you want to move faster through the cabin, and Southwest will deliver it to baggage claim when you land.

International flights and the same size rules

Southwest's carry-on size limit of 24 by 16 by 10 inches applies to all flights, including international routes. Some international airlines have smaller limits, but Southwest does not change its policy for flights to Mexico, the Caribbean, or Central America. If you're connecting to another airline, that airline's carry-on rules explore to the connecting flight, not Southwest's rules.

Check the other airline's website before you travel if you're making a connection. A bag that passes Southwest's check might be too large for your connecting carrier, and you'd have to check it at the connection point instead of at your origin airport.

Frequently Asked Questions

Can I bring a rolling suitcase as my personal item?

Only if it's very small — small enough to fit under the seat in front of you. Most rolling suitcases are considered carry-on bags, not personal items. A small rolling bag designed for underseat storage might work, but a standard carry-on rolling bag takes up your one free carry-on allowance.

Do wheels and handles count toward the 24-by-16-by-10 measurement?

No. The measurement is the bag itself at its widest points. Wheels, handles, pockets, and straps that extend beyond the bag's main body do not count. Measure the bag's length, width, and depth without including anything that sticks out.

What if I pack my bag so it's compressed and smaller than 24 by 16 by 10?

The bag is measured in its normal state, not compressed. If your bag's maximum dimensions exceed the limit, it will be checked even if you've packed it tightly. Soft-sided bags are measured at their widest point when packed normally.

Can I bring a backpack as a carry-on instead of a rolling bag?

Yes. A backpack that's 24 by 16 by 10 inches or smaller counts as a carry-on bag. You still get one free carry-on and one personal item, so you could bring a backpack as your carry-on and a purse or small bag as your personal item.

Do I need to remove my carry-on bag from the overhead bin if the flight is full?

No. If the overhead bin is full when you board, a gate agent will ask for volunteers to gate-check bags. If you don't volunteer, your bag stays with you. If the bin is completely full and no one volunteers, the gate agent will check bags starting with the last people to board.