What the Southwest Plus Size Policy Really Means: A 2026 Guide to the Customer of Size Program

Southwest Airlines offers a unique "Customer of Size" policy that allows passengers who require more than one seat to obtain the additional space at no extra cost. By purchasing a second seat in advance and requesting a refund after travel—or requesting a complimentary seat at the gate—passengers ensure their own comfort and the comfort of those around them.

For years, the "Southwest plus size policy" has been a topic of significant discussion within the travel community. Formally known as the Customer of Size (CoS) policy, it remains the most accommodating program of its kind in the United States aviation industry. As of 2026, while other airlines have moved toward more restrictive seating policies or "basic economy" tiers that penalize those needing extra space, Southwest has maintained this policy as a cornerstone of its commitment to passenger dignity and operational efficiency.

Understanding what this policy "really means" requires looking past the surface-level descriptions. It is not merely a "free seat" giveaway; it is a structured logistical framework designed to prevent seat encroachment, ensure safety during taxi, takeoff, and landing, and streamline the boarding process for all passengers.

The Core Philosophy: Encroachment and Comfort

The fundamental trigger for the Southwest Customer of Size policy is the concept of encroachment. Southwest defines a Customer of Size as anyone who occupies any portion of the adjacent seat. This is not strictly based on a passenger's weight or body mass index (BMI) but rather on the physical reality of how they fit into a standard airline seat.

If a passenger’s body extends beyond the armrest—which serves as the definitive boundary between seats—they are eligible for the policy. The goal is to ensure that every passenger on the aircraft has access to the full width of the seat they paid for. By providing a second seat to those who need it, Southwest eliminates the physical discomfort and social friction that often occurs when a passenger is forced to squeeze into a space that is too small.

From a technical standpoint, this policy also addresses safety. A passenger must be able to lower the armrest and properly secure their seatbelt (with or without an extender) to be safely transported. If the armrest cannot be lowered because of a passenger's size, that passenger is technically encroaching and is required by the policy to have an additional seat.

How the Policy Functions in 2026

There are two primary ways to utilize the Customer of Size policy. Each has its own set of procedures, benefits, and risks.

1. The Proactive Approach: Booking in Advance

The most recommended method is to purchase the additional seat at the time of booking. This is the only way to guarantee that the extra space will be available on the flight.

• The Process: When booking online or via the Southwest app, the passenger selects two seats. The second seat is booked under the same name, typically using the middle name "XS" (Extra Seat). For example, a passenger named John Quincy Adams would book one seat as "John Adams" and the second as "John XS Adams."
• The Cost: The passenger pays the full fare for both seats at the time of booking.
• The Refund: After the travel is completed, the passenger contacts Southwest (via email, phone, or the website) to request a refund for the second seat. In 2026, Southwest’s automated systems have made this process significantly faster, often processing the refund within 5 to 7 business days.
• The Benefit: Even if the flight is 100% sold out, the passenger is guaranteed their two seats. Southwest honors the refund regardless of the flight’s load factor—meaning even if the flight was full, you still get your money back for the second seat.

2. The Reactive Approach: Requesting at the Airport

Passengers also have the option to discuss their seating needs with a Customer Service Agent at the departure gate.

• The Process: If a passenger has not pre-booked a second seat but realizes they need one, they can ask the gate agent if the flight has the capacity to accommodate a second seat at no charge.
• The Risk: This approach is subject to availability. If the flight is oversold or completely full, the agent may not be able to provide the extra seat. In such cases, the passenger might be required to wait for a later flight with available space.
• The Benefit: There is no upfront cost for the second seat.

Technical Specifications: Seat Dimensions and Fleet Variations

To understand why the policy is necessary, one must look at the physical dimensions of Southwest’s fleet. As of 2026, Southwest exclusively operates the Boeing 737 family, but seat dimensions vary slightly between models.

The standard 17.8-inch width on the MAX series is slightly more generous than older 700-series aircraft, but it still presents a challenge for many travelers. The "Customer of Size" policy effectively turns two 17.8-inch seats into a single 35.6-inch space (minus the width of the retracted armrest), providing ample room for comfort and safety.

The Logistics of Boarding and Seating

Utilizing the policy affects how you interact with the crew and the aircraft itself. Because Southwest has an open-seating policy, there are specific protocols to ensure your "Extra Seat" is respected by other passengers.

The "Reserved" Seat Indicator

When you check in at the airport (either at the kiosk or the counter), the agent will provide you with a special document—often a second boarding pass or a "Seat Reserved" card. Once you board the aircraft, you place this card on the seat next to you. This signals to other passengers that the seat is intentionally left empty and is not available for boarding.

Pre-boarding Privileges

Customers of Size are generally eligible for pre-boarding. This allows the passenger to board before the main groups (A, B, and C) to find a row where they can comfortably occupy two seats. Usually, this means choosing a middle and aisle seat or a middle and window seat. The armrest between the two seats is then raised to create the extra space.

It is important to note that the armrest between the two seats must be able to be raised. On certain rows, such as the bulkhead (the very first row) or exit rows, the armrests are fixed and contain the tray tables. Therefore, Customers of Size are typically advised to avoid these rows, as the extra space cannot be unified.

Financial and Legal Context

Why does Southwest offer this when other airlines charge for every inch of space? The answer is a mix of passenger rights advocacy, operational efficiency, and brand positioning.

1. Operational Efficiency: When an airline forces a passenger into a seat that is too small, it often leads to "gate delays." If a passenger cannot fit, the flight attendants must find a solution while the plane is at the gate, which can delay takeoff. By encouraging passengers to book two seats in advance, Southwest ensures the plane is loaded correctly and departs on time.
2. Safety Regulations: The Federal Aviation Administration (FAA) requires that all passengers be able to sit with their seatbelts fastened and armrests down if they are encroaching on another passenger's space. Southwest's policy provides a clear, non-punitive path to meeting these safety requirements.
3. Market Differentiation: Southwest has long marketed itself as the "friendly" airline. In a 2026 travel landscape where "junk fees" and "shrinkflation" of seats are common, the Customer of Size policy remains a powerful tool for customer loyalty among a significant demographic of travelers.

Common Misconceptions and Mistakes

Even with a clear policy, travelers often encounter hurdles. Avoiding these common mistakes can make the process much smoother.

• Forgetting to Request the Refund: Southwest does not automatically refund the second seat. You must proactively reach out to their customer relations department after your trip is complete.
• Booking Through Third Parties: If you book through a site like Expedia or Priceline, the "XS" naming convention might not be recognized by the system. It is always safest to book "Extra Seat" tickets directly through the Southwest Airlines website or via their dedicated booking line.
• The Seatbelt Extender Myth: Some believe that if you use a seatbelt extender, you are automatically a "Customer of Size." This is not true. You can use an extender and still fit within the confines of a single seat. The policy only applies if you physically encroach on the neighboring seat's space.
• Expectations on Other Airlines: It is a common mistake to assume this policy applies elsewhere. Most other US carriers (Delta, United, American) require you to pay for a second seat at the prevailing rate, and they rarely offer a refund unless the flight has a certain number of empty seats, and even then, it is not a guaranteed policy like Southwest's.

Step-by-Step: Managing Your Refund in 2026

To ensure you get your money back for the proactive purchase of a second seat, follow these steps:

1. Complete Your Travel: Ensure both legs of your journey (if it's a round trip) are finished.
2. Gather Your Information: You will need your confirmation number, the dates of travel, and the flight numbers.
3. Contact Southwest Customer Relations:
   
   
   • Online: Use the "Contact Us" form on the Southwest website. Select "Refund" as the topic.
   • Phone: Call 1-800-I-FLY-SWA.
4. State the Policy: Explicitly mention that you are requesting a refund for an additional seat purchased under the "Customer of Size" policy.
5. Verify the Amount: Ensure the refund includes not just the base fare, but also the taxes and fees associated with that second seat.

Frequently Asked Questions

Does the policy apply to international flights?

Yes. Southwest’s Customer of Size policy applies to all flights operated by Southwest Airlines, including international destinations in Mexico, Central America, and the Caribbean. However, the refund process for international taxes can sometimes be more complex due to varying country regulations, so it may take slightly longer to process.

Can I use the extra seat for a child or a pet?

No. The Customer of Size policy is specifically for the physical accommodation of a single passenger who requires more than one seat. If you want a seat for a child or a pet (in a carrier), those fall under different ticketing and fee structures. The "Extra Seat" must remain empty to provide the necessary space for the primary passenger.

What if the flight is full and I didn't book an extra seat?

If you arrive at the gate and the flight is full, the gate agent may not be able to accommodate your request for a free second seat. In this scenario, you may be asked to take a later flight that has two adjacent seats available. This is why booking the second seat in advance is strongly recommended.

Do I get extra baggage allowance with two seats?

No. Even if you pay for two seats, the baggage allowance is tied to the passenger, not the number of seats purchased. On Southwest, this still means you get two checked bags for free, which remains the industry standard in 2026.

How does this work with Rapid Rewards points?

If you use points to book your travel, you will need to "purchase" the second seat using the same number of points. After your travel, those points are refunded back to your Rapid Rewards account.

Practical Recommendation for Travelers

If you believe you might encroach on an adjacent seat, always choose the proactive booking method. While it requires an upfront layout of cash or points, the peace of mind of having a guaranteed "reserved" seat next to you is invaluable. The stress of waiting at a gate to see if a flight is "too full" to accommodate your needs can ruin the start of a trip.

By 2026, the process for reclaiming those funds has become so streamlined that it is essentially a temporary deposit to ensure your comfort. Remember to carry a printed or digital copy of your "Extra Seat" confirmation to show the gate agent, and don't hesitate to ask for a pre-boarding pass if it isn't automatically offered. This policy isn't a "loophole"—it is a legitimate service designed to make air travel accessible and comfortable for bodies of all sizes.