Southwest Airlines Carry On Measurements vs. Other Major Carriers

Southwest Airlines allows each passenger one carry-on bag and one personal item. What sets them apart is the physical size limit of the suitcase. While most major U.S. airlines cap carry-on height at 22 inches, Southwest extends that limit to 24 inches.

• Southwest Carry-On Size: 24 x 16 x 10 inches [1].

• Weight Limit: Southwest does not currently enforce a specific weight limit for carry-on bags, provided you can lift the bag into the overhead bin without assistance [2].

• Personal Item: Must fit under the seat in front of you. While Southwest doesn’t list exact dimensions for this, common items include purses, small backpacks, or laptop bags [1].

This extra two inches in height and two inches in width means Southwest passengers can often use “medium” suitcases that would be strictly prohibited in the cabins of other airlines. These generous policies are a core part of why airline loyalty programs for Southwest remain popular despite their lack of a traditional “First Class” cabin.

Most other major domestic carriers adhere to a stricter 22 x 14 x 9-inch limit. This standard is designed to maximize the number of bags that can fit “wheels-first” into modern overhead bins [3].

According to data compiled by U.S. News & World Report, even budget carriers like Frontier and Spirit sometimes allow wider bags (up to 18 inches) but charge significant fees for the privilege of using the overhead bin. Southwest remains the only major carrier to allow a 24-inch tall bag for free for all passengers [3].

On travel communities like Reddit, users frequently discuss the “hidden” benefits of Southwest’s larger allowance. Frequent flyers note that while Southwest allows 24-inch bags, using a bag that large on a connecting flight with a partner or another airline (like American or United) will almost certainly result in a forced gate-check.

Furthermore, Southwest’s open-seating model adds a layer of strategy to carry-on luggage. Because there are no assigned seats, those in later boarding groups (Group C) often find overhead bins full, even if their bags meet the 24-inch requirement. In these cases, Southwest gate-checks the bag for free, maintaining their “two bags fly free” promise. This is a significant point for families; as noted in our guide on how airlines cater to family travelers, Southwest’s flexible baggage and boarding policies often make them a top choice for parents.

Beyond standard suitcases, Southwest provides specific exemptions that align with TSA safety standards. Items that do not count toward your carry-on limit include:

• Child Restraint Systems (Car Seats): Allowed if a seat is purchased for the child [1].

• Assistive/Medical Devices: Walkers, canes, and CPAP machines do not count against the “one bag plus one personal item” rule.

• Breast Pumps: Southwest classifies breast pumps and milk as medical necessities which are exempt from bag limits [1].

For those worried about the safety of these devices during transit, it is helpful to review airplane safety measures every traveler should know to ensure your gear is stowed according to FAA regulations.

• Size Matters: Southwest allows 24 x 16 x 10 inches, which is 2 inches taller and 2 inches wider than the 22 x 14 x 9 inches allowed by Delta, United, and American.

• Weight is Secondary: Unlike international carriers, Southwest does not have a hard weight limit for carry-ons; the “lift test” is the primary rule.

• Personal Item Flexibility: While dimensions aren’t strictly defined, your personal item must fit entirely under the seat (roughly 18.5 x 8.5 x 13.5 inches on most Southwest Boeing 737s).

• The “Transfer” Trap: If your trip involves multiple airlines, pack for the smallest size limit (22 x 14 x 9) to avoid fees on the second leg of your journey.

Action Plan for Travelers

1. Measure and Include Wheels: Use a tape measure to check your bag from the floor to the top of the handle. Southwest’s 24-inch limit includes wheels [1].
2. Board Early: If you are bringing a max-sized 24-inch bag, check in exactly 24 hours early to secure a higher boarding position and ensure overhead bin space.
3. Cross-Check Airlines: If you usually fly Southwest but are switching to a legacy carrier for a specific trip, verify if your “Southwest-sized” bag needs to be checked.

Southwest’s carry-on policy remains the most generous in the domestic market. By providing an extra 640 cubic inches of space compared to the industry standard, it allows travelers to skip the checked-bag line entirely—provided they know how to measure their gear correctly.