Flying a Pet on Southwest Airlines: Fees, Carrier Rules & How to Book

Flying a pet on Southwest Airlines means bringing a small, vaccinated domestic cat or dog in an airline-approved carrier that fits under the seat in front of you, on a domestic U.S. flight, for a Pet Fare of $125 each way per carrier ($35 each way for interisland Hawaii flights), according to Southwest Airlines' official Optional Travel Charges page (accessed September 2026). Southwest does not carry pets as checked baggage or cargo — pets travel in the cabin only, with you.

This guide walks through Southwest's own published rules — fees, carrier requirements, booking steps, and the difference between a pet and a service animal — sourced directly from Southwest's support pages and the U.S. Department of Transportation. As of September 2026, Southwest's policy pages state that pricing is “subject to change at any time,” so always confirm current fees when you book.

Southwest Airlines Pet Policy at a Glance

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

Southwest's official Optional Travel Charges page lists the in-cabin Pet Carrier charge as $125 per pet carrier for one-way travel on U.S. mainland flights, and $35 per carrier for interisland Hawaii routes. The fee applies per carrier, not per animal, so two eligible pets sharing one carrier still cost a single $125 fare. Southwest also sells a compliant soft-sided carrier at the ticket counter for a one-time $58 charge if you need one on the day of travel. The Pet Fare must be paid at the airport ticket counter with an accepted credit card — cash, gift cards, flight credit, and LUV Vouchers are not accepted — and Southwest states the fare is refundable if your reservation is cancelled.

Third-party travel sites report that Southwest's pet fee was $95 each way as recently as 2025 before rising to $125; Southwest's current policy page (accessed September 2026) confirms $125 is the fare in effect now, and explicitly warns that pricing is subject to change, so re-check the Optional Travel Charges page close to your travel date.

Which Pets Are Eligible to Fly with Southwest?

Southwest's Pet Policy support article limits in-cabin pet travel to “small, vaccinated domestic cats and dogs” at least eight weeks old. Household birds and other species are not covered under the standard pet policy. Southwest's additional pet-travel guidance also flags that pets with heart disease, anxiety disorders, or brachycephalic (flat-faced) airways — such as bulldogs, pugs, and Persian cats — face a higher risk of complications in flight, and states plainly: “you and your vet are best suited to determine if your pet can travel safely.” Animal Passport does not provide veterinary clearance or fitness-to-fly determinations; that decision rests with a licensed veterinarian.

Carrier Requirements

Southwest's Pet Policy support page requires that pets remain secured — including head and tail — inside an appropriate carrier at all times in the gate area, during boarding and deplaning, and for the full flight, and that the carrier be stowed under the seat in front of you. Southwest recommends soft-sided carriers because under-seat space varies by seat type, with aisle seats offering the least room.

Southwest's own policy pages do not publish an exact maximum carrier dimension. Carrier vendors marketing “Southwest-approved” products, and several third-party travel guides, commonly cite a maximum of approximately 18.5″ L x 13.5″ W x 9.5″ H as the practical under-seat limit — but because this figure does not appear on Southwest's official policy pages as of September 2026, confirm exact sizing with Southwest directly before purchasing a carrier. Both hard-sided and soft-sided carriers are accepted as long as they are leak-proof, well-ventilated, and the animal can stand and turn around comfortably inside.

A pet carrier counts as your one carry-on or personal item — you may bring either a pet carrier plus a personal item, or a pet carrier plus a regular carry-on bag, not both a carry-on and a personal item in addition to the carrier.

How to Book a Pet on Southwest Airlines

1. Reserve early. Southwest limits the number of pet carriers allowed per flight and accepts them on a first-come, first-served basis, so book as soon as your travel dates are set.
2. Add the pet to your reservation. Call Southwest at 1-800-I-FLY-SWA (1-800-435-9792) or add the pet carrier during online booking.
3. Confirm your carrier meets under-seat requirements for your specific aircraft and seat type before you leave for the airport.
4. Pay the Pet Fare at the ticket counter with a credit card on the day of travel — this cannot be prepaid online or covered by travel credits, per Southwest's official policy.
5. Go through security with your pet. Southwest's airport guidance instructs travelers to carry the pet through the walk-through screening device while the carrier is X-rayed separately; all carriers are subject to search.
6. Keep the pet in the carrier from the gate area through boarding, deplaning, and the entire flight — pets cannot be held or walked in the cabin, and cannot occupy exit rows or bulkhead rows.

Pets vs. Service Animals on Southwest

Southwest's pet fees and carrier rules do not apply to trained service animals. Under the U.S. Department of Transportation's 2020 Service Animal Final Rule (14 CFR Part 382, Subpart EE), airlines may recognize only dogs individually trained to perform tasks for a person with a disability as service animals; general comfort or companionship does not qualify. That same 2020 DOT rule change removed the prior requirement that airlines accommodate emotional support animals (ESAs) as a distinct, non-pet category — Southwest's current guidance notes that customers traveling with an ESA now need a complete, current letter from a licensed medical or mental health professional and, functionally, are handled outside the standard pet fare framework. Because airline and DOT service-animal rules change periodically, confirm current requirements directly with Southwest before travel.

State Entry Rules and Health Paperwork

Southwest requires pets to be vaccinated but does not itself set interstate veterinary paperwork requirements. The United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) states that it “doesn't regulate the interstate movement of pets by their owners” — instead, each destination state or territory sets its own health certificate, vaccination, or testing requirements, and travelers should contact the state veterinarian's office at their destination or their own veterinarian before flying. This is a different framework from Southwest's boarding rules, so check both.

Flying a Pet vs. Other Ways Pets Are Identified for Travel

It's worth distinguishing two very different things that both get called a "pet passport." A European Union pet passport, issued under the EU's official pet travel scheme, is a government-recognized document tied to a microchip, rabies vaccination record, and veterinary sign-off for cross-border EU travel — Southwest's domestic pet fare has nothing to do with that EU scheme, and Southwest does not issue or require any equivalent document for its U.S. domestic flights.

Separately, Animal Passport is a phone-based digital identification tool that uses muzzle biometrics — a nose print unique to each animal, similar to a human fingerprint — to bind an owner's record to a specific animal, along with breed, an estimated age from a dental photograph, a body condition score from a side-profile photo, and vaccination history. It 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 a livestock identification product, not a government travel document, and it is not an accepted substitute for Southwest's boarding requirements, a USDA APHIS health certificate, or an EU pet passport. For background on official U.S. pet travel paperwork, see Animal Passport's guide to USDA APHIS pet travel documents, and browse more explainers on the Animal Passport blog.

Common Mistakes to Avoid

• Assuming you can prepay the pet fare online. Southwest requires payment at the airport ticket counter by credit card, on the day of travel.
• Booking pet travel at the last minute. Southwest limits pet carriers per flight on a first-come, first-served basis, so late requests risk being turned away.
• Buying a carrier without checking under-seat fit for your specific flight. Under-seat space varies by aircraft and seat type; Southwest itself recommends soft-sided carriers for flexibility.
• Confusing an emotional support animal with a service animal. Since DOT's 2020 rule change, ESAs are not exempt from pet policies the way trained service dogs are.
• Assuming Southwest sets your destination's health paperwork rules. That's determined by the destination state, per USDA APHIS, not by the airline.

Frequently Asked Questions

How much does Southwest Airlines charge to fly with a pet?

Southwest charges a Pet Fare of $125 per carrier each way on U.S. mainland flights, and $35 per carrier each way for interisland Hawaii flights, according to Southwest's official Optional Travel Charges page (accessed September 2026). Pricing is subject to change, so confirm the current fare before booking.

Can two pets travel in one carrier on Southwest?

Yes. Southwest's Pet Policy allows up to two small cats or dogs of the same species inside a single pet carrier, and the $125 Pet Fare applies per carrier, not per animal.

Does Southwest allow pets as checked baggage or cargo?

No. Southwest's official policy states pets travel in the cabin only; the airline does not offer cargo or checked-baggage transport for pets.

Can I bring my pet on an international Southwest flight?

No. Southwest's pet policy applies to domestic U.S. flights only and does not cover international routes.

Is an emotional support animal the same as a service animal on Southwest?

No. Under the U.S. Department of Transportation's 2020 Service Animal Final Rule, only trained dogs performing disability-related tasks qualify as service animals exempt from pet policies; emotional support animals no longer receive that exemption.

Do I need a health certificate to fly my pet on Southwest?

Southwest requires pets to be vaccinated, but specific health certificate requirements are typically set by your destination state, not by Southwest or USDA APHIS, according to USDA APHIS's interstate pet travel guidance.

Is Animal Passport a substitute for Southwest's pet travel requirements?

No. Animal Passport is a biometric livestock identification tool using muzzle nose-print recognition; it is not a government-issued travel document and is not an accepted substitute for Southwest's boarding rules or USDA paperwork.

How many pet carriers does Southwest allow per flight?

Southwest limits the number of pet carriers accepted per flight and books them on a first-come, first-served basis, so the airline recommends reserving pet travel as early as possible.