Southwest Airlines Carry-On Baggage Rules & Size

Quick answer: The Southwest Airlines carry-on baggage rules allow one carry-on bag up to 24 × 16 × 10 inches, including wheels, handles, and attachments, plus one personal item that fits under the seat in front of you. That is roomier than the common U.S. 22 × 14 × 9 limit, but it is not a reason to buy the largest bag possible: a Southwest-sized bag can be too large for the airline on your return flight, a partner segment, or a future trip.

Last reviewed July 27, 2026. Southwest’s fare rules, flight operations, and baggage policies can change. Confirm the details attached to your specific reservation before departure.

Southwest Carry-On Rules at a Glance

Southwest’s official carry-on and personal-item policy is the final source. It confirms one overhead carry-on, one under-seat personal item, and the 24 × 16 × 10 maximum including all exterior parts.

Is a 24-Inch Suitcase Carry-On Size on Southwest?

It can be, but only when the full exterior dimensions are no more than 24 × 16 × 10 inches. “24-inch luggage” describes a product category and often refers to the shell height. Southwest measures the real packed bag. Wheels, telescoping-handle housing, protective feet, side handles, exterior pockets, and expansion all count toward the final size.

That means a 24-inch suitcase is not automatically approved. Measure it fully packed on its height, width, and depth. A suitcase that is 24 inches tall but 11 inches deep after an expansion zipper is opened does not fit the stated maximum. The best approach is to leave a margin, especially when packing soft-sided bags that can bulge outward.

Southwest’s Bigger Allowance: Useful, but Not Universal

Southwest’s 24 × 16 × 10 allowance is more generous than the 22 × 14 × 9 limit used by American, Delta, United, and JetBlue. That extra space is useful for a domestic Southwest-only trip, a family traveling with more clothes, or a traveler trying to avoid checked baggage. It becomes risky when the bag will fly on another carrier.

A 24 × 16 × 10 suitcase can exceed another airline’s limit by two inches in height, two inches in width, and one inch in depth. Choose it only when Southwest is the relevant rule for the whole journey. If your outbound is Southwest but your return, connection, or future trips commonly use other airlines, a true 22 × 14 × 9 carry-on gives you much more flexibility.

Southwest Personal Item Rules

Southwest says the personal item must fit under the seat in front of you. A purse, briefcase, laptop case, small backpack, or small camera bag are common examples. Because the official policy emphasizes under-seat fit rather than a universal published measurement, do not treat a large travel backpack or an under-seat roller as automatically acceptable. Seat geometry and a fully packed bag both matter.

Make this the bag that stays with you if the overhead bin is full. Put documents, medication, electronics, chargers, a power bank, valuables, snacks, and a light layer in the personal item first. That keeps the trip manageable if boarding staff gate check the larger carry-on for space. Compare personal item bags and underseat carry-on luggage based on actual packed dimensions—not just a product title.

Are Southwest Carry-Ons Free?

Southwest’s cabin allowance is one carry-on and one personal item. That should not be confused with checked-bag pricing or a promise that every bag will remain in the overhead bin. A correctly sized carry-on can be gate checked when bins fill up. An oversized bag is a different issue: it may need to be checked because it does not meet the stated carry-on rule.

Checked-bag benefits, status, card benefits, fare family, route, and booking date can affect the price and allowance for bags in the cargo hold. Use the baggage details in your booking and Southwest’s current terms for the exact trip instead of relying on old “Bags Fly Free” summaries. The fact that your cabin bags are included does not eliminate the need to measure them carefully.

Does Southwest Have a Carry-On Weight Limit?

Southwest’s carry-on policy focuses on size and whether the bag can be stored in the cabin. A bag still needs to be practical to lift and safe to place in the overhead bin. Do not confuse the absence of a general published cabin-bag weight number with permission to overpack a suitcase you cannot handle.

Use a lighter suitcase if you pack dense clothing, cameras, or work equipment. A luggage scale is helpful when another airline on the itinerary has a stated weight limit or when you are deciding what should remain in the cabin. Our carry-on weight-limits guide compares the situations where weight can matter more than dimensions.

How to Pack for Southwest Without Creating a Return-Flight Problem

1. Verify every operating carrier, not just the airline that sold the ticket.
2. Measure the complete packed carry-on, including wheels and expansion.
3. Keep the personal item compact enough to slide fully under the seat.
4. Place critical items in the personal item before you reach the gate.
5. Use a 24 × 16 × 10 bag only when that allowance works for the full itinerary.
6. Choose a 22 × 14 × 9 or 20-inch bag when flexibility matters more than maximum packing space.
7. Check the bag policy again if the booking changes to a partner-operated flight.

What Happens if the Overhead Bins Are Full?

A compliant carry-on can be checked at the gate because cabin space runs out. That is not the same as a bag being rejected for exceeding the size limit. Prepare as though it could happen: keep documents, medication, fragile items, and valuable electronics under the seat. When a bag is checked at the gate, follow the staff instructions about whether to collect it on the jetbridge or at baggage claim.

Boarding timing and aircraft layout can affect bin availability, but the durable solution is not a boarding “hack.” It is an organized personal item that contains everything you need while seated and a roller that remains within the actual published size. That strategy works even when a flight is full.

Southwest Partner Flights and Connections

Southwest explicitly notes that a partner airline can use different carry-on and personal-item guidelines. A Southwest allowance is not transferable to an operating partner. Open the reservation, read the operating-carrier line on every segment, and check the stricter carrier’s policy before buying or packing a large bag.

International trips deserve the same caution. International carriers may use a smaller cabin size, a stated weight maximum, or a combined allowance for both cabin bags. Use the international carry-on size guide and our Airline Carry-On Rules Center when a connection is involved.

Measure the Bag the Way the Airport Sizer Does

Set the packed suitcase upright on a flat floor. Measure from the floor to the highest fixed point, then across the widest point, then from the frontmost packed pocket to the backmost wheel or shell. Do not use the product’s “carry-on” marketing label as the final measurement. A soft-sided bag can grow at the front pocket; a hard-shell bag can have wheel housings that add height; an expandable zipper can add depth even when it looks only slightly open.

Southwest’s 10-inch depth limit is the measurement most likely to be lost after packing. Keep shoes, bulky layers, and dense toiletries inside the shell rather than forcing them into an exterior pocket. If you need the expansion zipper, the bag should still be measured after it is open. The safer answer is to pack less, not to hope that a bulging bag will be treated as smaller than it is.

Cabin Bags Versus Checked Bags: Make the Fare Decision Before Packing

A cabin-bag plan saves time at the carousel and keeps important items closer, but it is not automatically the right solution for every trip. A traveler carrying formalwear, equipment, gifts, or more than a week of clothing may be better served by checking a bag deliberately rather than trying to stretch the carry-on rules. Review the current baggage allowance and price on the exact booking before the airport; the right choice can depend on fare, status, card benefits, and how many travelers are sharing luggage.

When you do carry on, choose the bag around the itinerary. Southwest’s larger allowance is helpful, but a compact roller can be the better investment if you regularly fly American, Delta, United, JetBlue, or international airlines. A reusable bag choice is often more valuable than squeezing an extra outfit into a suitcase that only works on one airline.

Families, Pets, and Special Items

Family travel changes the packing plan. American travelers should confirm Southwest’s current child, stroller, car-seat, breast-pump, and medical-device rules directly instead of assuming every item uses the ordinary two-bag allowance. The same is true for pet travel: Southwest’s carry-on policy states that the pet carrier counts as either the carry-on or the personal item, so a traveler with a pet must design the other bag around the remaining allowance.

Keep vital family and medical items in the bag that stays below the seat. That protects the things you may need during the flight when a larger roller must be placed in an overhead bin or is gate checked for lack of space. Special-item policy details can change, so treat the airline’s current written guidance and your reservation as controlling.

Southwest Carry-On Decision Table

FAQ: Southwest Carry-On Rules

What size carry-on can I bring on Southwest?

Southwest publishes a maximum of 24 × 16 × 10 inches for one overhead carry-on, including wheels, handles, and attachments.

Can I bring a backpack and a carry-on on Southwest?

Yes, if the backpack fits under the seat as your one personal item and the other bag meets the carry-on rule.

Is a 24-inch suitcase always allowed on Southwest?

No. The full outside suitcase must be at or below 24 × 16 × 10 inches after it is packed.

Does Southwest have a carry-on weight limit?

Its general carry-on policy focuses on the size rule and cabin storage. You should still be able to handle the bag safely and check any different rule on a partner segment.

Will my bag fit on every airline if it fits Southwest?

No. Southwest’s allowance is larger than many U.S. airline limits. A 22 × 14 × 9 bag is the safer cross-airline target.

Does a pet carrier count as a personal item?

Southwest says a pet carrier counts as either the carry-on bag or personal item, so plan your two-bag allowance around it.

Final Verdict

Southwest gives travelers a generous 24 × 16 × 10 carry-on limit, but the smartest bag is the one that works for the entire trip. Use the roomier allowance on a Southwest-only journey, keep essentials in a true under-seat personal item, and step down to a 22 × 14 × 9 or compact 20-inch roller when another airline is part of the equation.

As an Amazon Associate, we may earn from qualifying purchases.