Pets on Southwest Airlines: Fees, Carrier Size, and Booking Rules

Pets on Southwest Airlines means small, vaccinated domestic cats and dogs may fly in the cabin only on qualifying U.S. domestic flights, in an under-seat carrier, for a Pet Fare of $125 per carrier on the U.S. mainland and $35 per carrier between Hawaiian Islands, according to Southwest Airlines Optional Travel Charges as of September 2026. Southwest Airlines does not accept pets in cargo, on international itineraries, or on flights between the continental United States and Hawaii. As of September 2026, book the pet by phone, pay at the ticket counter, and keep the animal fully inside the carrier from gate to landing.

This guide is published by Animal Passport for travelers researching airline pet rules. It summarizes Southwest Airlines Help Center articles, the Southwest Airlines Contract of Carriage, United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) air-travel guidance, and U.S. Department of Transportation (DOT) service-animal rules. It is not veterinary or legal advice. Policies change; confirm fees and destination rules on Southwest.com before you fly.

What “pets on Southwest Airlines” covers

Pets on Southwest Airlines refers to the airline’s in-cabin pet program for companion cats and dogs that meet age, vaccination, carrier, and route rules—not cargo shipping, and not trained service dogs traveling under disability accommodations.

According to the Southwest Airlines Pet Policy Help Center article (retrieved September 2026), Southwest welcomes small, vaccinated domestic cats and dogs in an appropriate pet carrier in the cabin on domestic flights. Pets must be at least eight (8) weeks old. No pets are transported in the cargo compartment. Unaccompanied Minors cannot travel with a pet. Space is limited, and Southwest recommends making a reservation in advance by calling the airline.

The Southwest Airlines Contract of Carriage (Passenger) states the same core limits: one pet carrier per passenger; up to two animals of the same species per carrier; a right to limit pet carriers to six (6) per flight on a first-come, first-served basis; no cargo pets; no pets on international itineraries; and no pets on itineraries between the continental United States and Hawaii.

Southwest pet fee (as of September 2026)

As of September 2026, Southwest Airlines Optional Travel Charges lists a one-way carry-on Pet Charge of $125 per pet carrier for U.S. mainland travel and $35 per pet carrier for travel between Hawaiian Islands. Southwest notes that Pet Fare pricing is subject to change at any time. The Southwest Airlines Pet Policy states the Pet Fare must be paid at the Southwest ticket counter with accepted credit cards and is refundable if you cancel your reservation.

Southwest Airlines Optional Travel Charges also lists a ticket-counter Pet Carrier item for sale at $58 per carrier. That is a product purchase, separate from the Pet Fare charged to transport a pet.

Southwest Airlines accepts small vaccinated domestic cats and dogs to travel as pets. All in-cabin pets must be carried in an appropriate carrier. Each pet carrier counts as a carryon or personal item. Pet Fare is subject to change at any time. — Southwest Airlines Optional Travel Charges, footnote on pets (2026)

Carrier size and packing rules

Southwest Airlines’ “What type of pet carrier can I bring?” Help Center article (retrieved September 2026) requires carriers that are specifically designed as pet carriers, leak-proof, and well ventilated, and that fit under the seat in front of you. The cat or dog—including head and tail—must stay completely inside and be able to stand up and move around with ease.

Official maximum dimensions published on that Southwest Airlines Help Center page are:

• Southwest Airlines Pet Carrier: 15" (L) × 10" (W) × 10" (H)
• Other pet carriers: maximum 18" (L) × 10.5" (W) × 10" (H)

Source disagreement note: Some third-party travel blogs cite different under-seat limits (for example, 18.5" × 13.5" × 8.5"). Those figures do not match Southwest Airlines’ Help Center dimensions retrieved for this article. For boarding decisions, follow Southwest Airlines’ published Help Center measurements and the Contract of Carriage requirement that the carrier fit under the seat in front of you.

Southwest recommends a soft-sided carrier because under-seat space varies by seat type and location; aisle seats may have more limited space. Pet carriers count as either a personal item or a carry-on item. You may board with a pet carrier plus a personal item, or a pet carrier plus a regular-size carry-on bag, according to Southwest Airlines airport and carrier Help Center articles.

How to book pets on Southwest Airlines

1. Confirm eligibility. Only small vaccinated domestic cats and dogs at least eight weeks old; cabin only; no unaccompanied-minor pet travel (Southwest Airlines Pet Policy; Contract of Carriage).
2. Check the route. Pets are not accepted on international itineraries or between the continental United States and Hawaii. Inter-island Hawaii flights may accept pets; mainland–Hawaii does not (Southwest Airlines destination pet article; Contract of Carriage §6.e(8)).
3. Call Southwest to reserve the pet. The Contract of Carriage states pet reservations can only be booked by calling Southwest. Space is first-come, first-served, with a typical six-carrier flight cap.
4. Arrive early and check in at the ticket counter. Pay the Pet Fare before going to the gate (Contract of Carriage; airport expectations Help Center article).
5. Screen at security. Southwest’s airport expectations article states you hold your pet and walk through screening while the carrier is X-rayed; carriers may be searched.
6. Board with your group. Keep the pet fully inside the carrier under the seat for the entire flight.

Hawaii, international, and other destination limits

As of September 2026, Southwest Airlines’ destination requirements for pets state: pets are not allowed on flights to or from Hawaii; pets are accepted on flights between Hawaiian Islands; and pets are not allowed on international flights or any itinerary that includes an international flight. The Contract of Carriage mirrors the continental–Hawaii ban and the international ban.

For inter-island Hawaii travel, Southwest points travelers to State of Hawaii pet policy and procedures. USDA APHIS FAQ guidance for accredited veterinarians (last modified July 30, 2025) states that APHIS does not set or endorse health certificates for pet movement across U.S. state or territorial lines; each state or territory—including Hawaii, Guam, Puerto Rico, and the U.S. Virgin Islands—sets its own requirements. Contact the destination’s state animal health official for certification rules that apply beyond the airline’s cabin policy.

Southwest’s destination article also notes that Customers traveling to Puerto Rico may face specific requirements. Verify those with Southwest and territorial animal-health authorities before booking.

Day-of-travel and onboard rules

Southwest Airlines airport and onboard Help Center articles (retrieved September 2026) and the Contract of Carriage require:

• Pet fully secured in the carrier (including head and tail) in the gate area, during boarding and deplaning, and for the entire flight
• Carrier stowed under the seat in front of you—not on a passenger seat, not in an exit row, and not in the first (bulkhead) row
• No exit-row seating and no seat without forward under-seat stowage for passengers traveling with a pet
• Disruptive behavior (scratching, excessive whining or barking, growling, biting, jumping, lunging, or eliminating in the cabin or gate area) may result in denied boarding

Southwest’s additional pet-policy information article states that air travel can be stressful and that animals with heart disease, anxiety disorders, or brachycephalic (short-nosed) airways are more susceptible to complications during flight. You and your veterinarian are best suited to decide whether your pet can travel safely. That is airline guidance, not a diagnosis.

USDA APHIS “Pets on Planes” Lesson 1 (last modified January 25, 2026) similarly notes that short-nosed (brachycephalic) dogs and cats can face higher risk of heat stroke and breathing problems under stress or extreme heat, and that USDA regulations require dogs and cats to be at least eight weeks old and fully weaned before traveling by air. Much of that APHIS lesson focuses on kennel labeling and documentation typical of cargo or checked-animal movement; Southwest does not offer cargo pet transport, so cabin-specific Southwest rules still control what you may bring onboard.

Pets vs. service animals (DOT rules)

Do not confuse a paid cabin pet with a trained service animal. Under the U.S. Department of Transportation Air Carrier Access Act (ACAA) final rule on traveling by air with service animals (Federal Register, December 10, 2020), a service animal is a dog, regardless of breed or type, that is individually trained to do work or perform tasks for a qualified individual with a disability. Emotional support animals, comfort animals, companionship animals, and service animals in training are not service animals under that definition; airlines may treat them as pets.

Trained service dogs travel under disability accommodations and documentation rules set by DOT and the airline—not under the Southwest Pet Fare program described above. If you need a service-animal accommodation, follow Southwest’s disability and service-animal procedures and DOT forms; do not book a Pet Fare expecting ESA privileges.

Comparison: cabin pet vs. what Southwest will not do

Health records, state rules, and identity documents

Southwest requires pets to be vaccinated but does not replace destination animal-health law. USDA APHIS reminds veterinarians that airlines sometimes require paperwork separate from country or state entry rules, and that for interstate U.S. movement APHIS does not endorse certificates—states and territories do (APHIS pet-travel FAQs, July 30, 2025). Carry current rabies and vaccination records when you travel, and ask your veterinarian whether a Certificate of Veterinary Inspection is required for your destination.

Airline pet rules and official government travel schemes are also different from digital livestock-identity products. Animal Passport is a digital animal and livestock passport that uses muzzle biometrics (a nose print unique like a fingerprint), phone-based capture, and records that bind owner, breed, estimated age, body condition, and vaccination history. Age can be estimated from a dental photograph with a confidence score, and body condition can be scored 1–5 from a side-profile photo. The product was used in livestock flood rescue in Pakistan in August 2025 so farmers could reclaim animals when paper tags washed away. It is not a Southwest Airlines travel document, not an EU pet passport, and not a government-issued PETS travel certificate. For airline boarding, follow Southwest and destination authorities; for durable animal identity and vaccination history in the field, see Animal Passport’s blog.

Practical checklist before you fly

• Measure your carrier against Southwest’s Help Center maximums (18" × 10.5" × 10" for non-Southwest carriers) and confirm it fits under your seat type.
• Call Southwest as soon as you buy tickets—six carriers per flight sell out.
• Budget $125 each way on mainland itineraries ($35 inter-island Hawaii), plus any ticket-counter carrier purchase if needed.
• Pack absorbent pads, a familiar blanket, and a printed vaccination record.
• Plan relief stops before security; Southwest states it will not hold a flight for a pet-relief visit.
• Skip exit-row and bulkhead seats when traveling with a pet.
• If your pet is brachycephalic, elderly, or anxious, consult your veterinarian before booking.

Last updated September 2026 by Animal Passport. Always verify the current Pet Fare and Help Center articles on Southwest.com, because optional charges and destination rules can change.