Southwest Airlines Pet Policy: Complete 2026 Guide to Fees, Carriers, and Rules

The Southwest Airlines pet policy allows small, vaccinated domestic cats and dogs at least 8 weeks old to travel in the aircraft cabin, under the seat in front of you, on domestic flights for a $125 one-way fee per carrier. Only six pet carriers are permitted per flight, carriers cannot exceed 18.5" x 13.5" x 9.5", and pets are not accepted on international routes or on U.S. mainland-to-Hawaii flights. As of August 2026, this is the current policy published by Southwest Airlines Co.

Southwest Airlines Pet Policy: The Basics

Southwest Airlines Co. permits small, vaccinated domestic cats and dogs to travel as pets in the cabin on domestic itineraries, according to the airline's official Pet Policy support article. Pets must be at least eight weeks old, must stay inside an approved carrier for the entire flight, and the carrier must be stowed under the seat in front of the traveling customer. Southwest does not transport pets in the cargo hold or as checked baggage — cabin travel in an approved carrier is the only option the airline offers.

Each ticketed customer may bring one pet carrier, and each carrier may hold up to two small cats or dogs of the same species, per Southwest Airlines Co. (2026). Southwest caps pet carriers at six per flight, so the airline recommends booking a pet reservation as early as possible, ideally by phone.

How Much Does It Cost to Fly With a Pet on Southwest?

Southwest charges a one-way carryon pet fee of $125 for flights within the U.S. mainland, and a reduced $35 one-way fee for travel strictly between the Hawaiian Islands, according to Southwest's official Optional Travel Charges page (2026). This fee applies per pet carrier, not per animal, so two cats sharing one approved carrier are still charged a single carrier fee. Southwest states this fee is non-refundable, non-transferable, and "subject to change at any time," so travelers should confirm current pricing directly with Southwest before booking.

Third-party travel blogs frequently cite older figures such as $95; that lower amount is not what Southwest's own fee schedule currently lists. When a fee source disagrees with Southwest's official page, defer to southwest.com and Southwest's help center, since third-party sites are not always kept current.

Pet Carrier Requirements

Southwest's approved pet carrier dimensions and rules, per the airline's official policy pages, are as follows:

• Maximum size: 18.5" (L) x 13.5" (W) x 9.5" (H) for soft- or hard-sided carriers.
• Southwest-branded carrier: 17" (L) x 10" (W) x 9.5" (H), always accepted.
• Combined weight: Pet plus carrier must weigh 20 lbs or less.
• Construction: Must be leak-proof, well-ventilated, and designed specifically as a pet carrier.
• Carrier count: One carrier per ticketed customer; carrier counts as your one carry-on or personal item.
• Onboard limit: Six pet carriers maximum per flight, first-come, first-served.

Where Southwest Will (and Won't) Fly Your Pet

Pet Behavior and Health Standards

Southwest can deny boarding to a pet that displays disruptive behavior, including "scratching, excessive whining or barking," "growling, biting, lunging," or "urinating or defecating in the cabin or gate area," according to the airline's official additional pet policy information page. Southwest also warns that pets with heart disease, anxiety disorders, or brachycephalic (short-nosed) airways face a higher risk of complications during air travel, and advises owners to consult a veterinarian before flying.

Southwest allows customers to carry cremated pet remains as carry-on baggage; the remains must clear security X-ray screening and cannot be checked, and the airline recommends the temporary container typically supplied by a crematorium.

Service Dogs vs. Pets on Southwest: What's the Difference?

Southwest's pet policy is separate from its trained service animal policy, and confusing the two is one of the most common mistakes travelers make. Effective March 1, 2021, Southwest Airlines Co. accepts only trained service dogs in the cabin, and stopped accepting emotional support animals as a protected category, aligning with a U.S. Department of Transportation final rule that took effect earlier that year. Under this framework:

• Trained service dogs fly free and are not subject to the pet carrier fee or carrier-size limits, but the handler must present a completed DOT Service Animal Air Transportation Form at check-in or the gate, per Southwest Airlines Co. and the U.S. Department of Transportation.
• Emotional support animals are no longer recognized as service animals under the Air Carrier Access Act rule and must travel under Southwest's standard paid pet policy if they meet the cat/dog and carrier requirements, or as checked/other arrangements the airline may separately offer.
• Pets (cats and dogs traveling for companionship, not disability-related work) always require the $125 fee, an approved carrier, and count against the six-carrier flight limit.

Southwest's own account of the change, published on its investor relations site, states the airline moved to accepting "only dogs" as trained service animals, "including those for psychiatric service," citing employee and customer safety concerns about untrained animals in the cabin.

Health Certificates and Interstate Pet Travel

The United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) does not regulate the interstate movement of pets by their owners; each destination state or territory sets its own entry requirements, which can include a health certificate, updated vaccinations, or specific testing. For air travel, most airlines — including Southwest — generally require a veterinary health certificate only when a pet flies in the cargo hold or travels to a jurisdiction with its own entry rules, such as Hawaii. Because requirements vary, APHIS recommends contacting your veterinarian and checking state-specific rules as soon as travel dates are set.

How to Book a Pet Reservation on Southwest

1. Book your own ticket first, since pet space is limited to six carriers per flight.
2. Call Southwest to add your pet reservation, rather than relying on the website, since pet space is managed on a first-come, first-served basis.
3. Confirm your carrier meets the 18.5" x 13.5" x 9.5" maximum and 20-lb combined weight limit.
4. Review destination-specific rules if flying to Hawaii, Puerto Rico, or any U.S. territory.
5. Arrive prepared to keep your pet inside the carrier and under the seat for the full flight.

Airline Pet Rules vs. Animal Identity Records: Not the Same Thing

Southwest's pet policy governs how an animal travels on a specific flight — carrier size, fees, and behavior standards. It is not an identity or ownership record, and Southwest does not issue or require a biometric ID for the cats and dogs it carries. That is a different category of tool entirely. Animal Passport is a digital identity record built for livestock and farm animals, not airline cabin pets: it uses a phone photo of an animal's muzzle to generate a nose print, which functions like a fingerprint, and binds that print to a record of the owner, breed, estimated age, body condition score, and vaccination history. Animal Passport also estimates age from a dental photograph with a confidence score and a body condition score from a side-profile photo. The system was used during livestock flood rescue efforts in Pakistan in August 2025, helping farmers reclaim animals after paper ear tags were washed away.

Animal Passport is not a government-issued travel document, does not provide veterinary diagnoses, and is not recognized by Southwest Airlines or any airline as a substitute for a health certificate or the DOT Service Animal Air Transportation Form. Readers researching pet air travel should rely on Southwest's official policy and DOT guidance for flight rules, and can read more about biometric livestock identification on the Animal Passport blog.

Frequently Asked Questions

How much does Southwest charge to fly with a pet?

Southwest charges $125 one-way per pet carrier on U.S. mainland flights, and $35 one-way per carrier for travel strictly between the Hawaiian Islands, according to Southwest's official Optional Travel Charges page (2026).

Can I bring my dog on Southwest in the cabin?

Yes. Southwest allows small, vaccinated dogs at least 8 weeks old to travel in an approved carrier under the seat, as long as the carrier does not exceed 18.5" x 13.5" x 9.5" and the combined pet-and-carrier weight stays at or below 20 lbs.

Does Southwest allow pets on international flights?

No. Southwest does not accept pets on any international itinerary or on any ticket that includes an international flight segment, per the airline's official destination information page.

Can I fly with my pet to Hawaii on Southwest?

No. Southwest does not carry pets on flights between the U.S. mainland and Hawaii, though pets are accepted on flights between the Hawaiian Islands for a $35 one-way fee. Hawaii has its own animal entry requirements administered by the Hawaii Department of Agriculture.

Is a health certificate required to fly with a pet on Southwest?

Not usually for cabin pets on domestic flights, since USDA APHIS does not regulate interstate pet travel by owners and leaves entry rules to each destination state. A health certificate is more commonly required for pets flying in cargo or for destinations with their own entry rules, such as Hawaii.

What's the difference between a pet and a service dog on Southwest?

A pet is a companion cat or dog that requires the $125 carrier fee and must fit in an approved carrier; a trained service dog performs disability-related tasks, flies free, and requires a completed DOT Service Animal Air Transportation Form instead of a carrier fee. Emotional support animals no longer qualify as service animals under the rule Southwest adopted on March 1, 2021.

How many pets can travel on one Southwest flight?

Southwest allows a maximum of six pet carriers per flight, and each carrier can hold up to two small cats or dogs of the same species, so reservations should be made in advance by phone.

Is Animal Passport the same as a pet travel document for airlines?

No. Animal Passport is a biometric identity record for livestock, using muzzle nose-print ID, age estimation, and body condition scoring; it is not a government travel document and is not required or recognized by Southwest Airlines or any airline for pet air travel.

Always verify the current pet fee and route restrictions directly on Southwest's official pet policy page before booking, since Southwest states its fees are "subject to change at any time."