Southwest Flying With Pets: Cabin Fees, Carrier Rules, and How to Book

As of September 2026, southwest flying with pets means bringing a small, vaccinated domestic cat or dog in the cabin on many Southwest Airlines domestic flights—not in cargo. Southwest Airlines defines its pet program as cabin-only travel for pets at least eight weeks old, with a Pet Fare of $125 per carrier one-way on U.S. mainland itineraries ($35 between Hawaiian Islands), advance phone booking, and a six-carrier per-flight cap under the Southwest Airlines Contract of Carriage.

This guide summarizes Southwest’s official pet rules, U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) interstate context, and how those airline rules differ from biometric livestock identity tools such as Animal Passport. It is not veterinary diagnosis or legal advice. Always reconfirm fees and destination rules on southwest.com before you travel.

What “southwest flying with pets” covers

Southwest flying with pets is Southwest Airlines’ in-cabin pet carriage program for small domestic cats and dogs. According to Southwest’s Pet Policy help article (opened September 2026), the airline 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; and Unaccompanied Minors cannot travel with a pet.

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; leak-proof, well-ventilated carriers that fit under the seat; and no pets on international itineraries or on itineraries between the continental United States and Hawaii.

Southwest pet fee (Pet Fare) as of September 2026

Southwest’s Optional Travel Charges page lists the one-way carryon pet charge as $125 per pet carrier for U.S. Mainland travel and $35 per pet carrier between Hawaiian Islands. Footnote 7 on that page (2026) states Southwest accepts small vaccinated domestic cats and dogs as pets, that all in-cabin pets must be carried in an appropriate carrier, that each pet carrier counts as a carryon or personal item, and that Pet Fare is subject to change at any time.

Southwest’s Pet Policy help article states the Pet Fare must be paid at the Southwest ticket counter with accepted credit cards, and that if you cancel your reservation, the Pet Fare is refundable. The Contract of Carriage adds that pet reservations can only be booked by calling Southwest, and that a passenger traveling with a pet must check the pet in at the airport ticket counter and pay the pet fare before proceeding to the departure gate.

Older third-party blogs still quote a $95 Southwest pet fee. Southwest’s live Optional Travel Charges page lists $125 (mainland) and $35 (interisland Hawaii) as of September 2026—use the airline’s fee page, not archived blog posts.

How to book a pet on Southwest (numbered steps)

1. Book your own Southwest ticket for a domestic itinerary where pets are accepted.
2. Call Southwest as early as possible to add the pet reservation (Contract of Carriage: pet reservations can only be booked by calling Southwest; space is limited).
3. Confirm destination rules: no mainland–Hawaii or international pet travel; interisland Hawaii pets are accepted with State of Hawaii procedures to follow separately.
4. On travel day, check in the pet at the airport ticket counter and pay the Pet Fare with an accepted credit card before going to the gate (Southwest Pet Policy and airport pet article).
5. At security, hold your pet and walk through screening while the carrier is X-rayed; carriers may be searched (Southwest airport pet expectations article).
6. Board with your assigned group; keep the animal fully inside the carrier (head and tail included) from the gate through the flight; stow the carrier under the seat in front of you.

Carrier size, seating, and onboard rules

Southwest’s approved pet carriers article (help center) requires carriers that are specifically designed as pet carriers, leak-proof, and well ventilated, and that fit under the seat so the animal can stand and move with ease. Published maximum dimensions on that page are:

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

Southwest recommends a soft-sided carrier because under-seat space varies by seat type and location; aisle seats may be tighter. Pet carriers count as either a personal item or a carryon item: you may board with a pet carrier plus a personal item, or a pet carrier plus a regular-size carryon bag (Southwest airport and carrier articles).

Onboard, Southwest’s onboard pet expectations article states pets must never occupy a passenger seat; may not be located in an exit row or the first row (bulkhead); must remain secured in the carrier for the entire flight; and may be denied boarding for disruptive behavior (examples include excessive barking, growling, biting, or eliminating in the cabin or gate area). The Contract of Carriage separately bars pet travelers from exit-row seats or seats with no forward under-seat stowage.

Some secondary travel sites list different carrier dimensions (for example, 18.5" × 13.5" × 8.5"). Those figures do not match Southwest’s help-center dimensions quoted above. Prefer Southwest’s published carrier article and a test fit under a Boeing 737-style seat before travel day.

Where pets are and are not allowed

USDA APHIS and state requirements (separate from Southwest fees)

Airline acceptance is not the same as animal-health entry rules. USDA APHIS states that APHIS does not regulate interstate movement of pets by their owners; destination states and territories set requirements such as health certificates, vaccinations, tests, or treatments (APHIS “Take a Pet from One U.S. State or Territory to Another,” last modified June 10, 2026 on the page opened for this article).

USDA APHIS “Pets on Planes” Lesson 1 (last modified January 25, 2026) notes that USDA regulations require dogs and cats to be at least 8 weeks old and fully weaned before traveling, and that some states and foreign countries require a rabies vaccination certificate signed by a licensed veterinarian. That lesson also discusses kennel suitability and documentation more typical of cargo-style shipping; Southwest does not accept pets as cargo, so cabin carrier rules on southwest.com control boarding even when APHIS cargo kennel guidance is useful background.

For Puerto Rico and other special destinations, follow both Southwest’s destination notes and the receiving jurisdiction’s animal-health rules via APHIS state pages and your veterinarian—without treating any digital ID app as a substitute for required certificates.

Service dogs vs. pets (DOT rules)

Under the U.S. Department of Transportation (DOT) Air Carrier Access Act service-animal final rule published in the Federal Register on December 10, 2020 (effective January 11, 2021), a service animal is defined as a dog individually trained to do work or perform tasks for a qualified individual with a disability. The rule allows airlines to treat emotional support animals as pets rather than service animals. Southwest’s pet Pet Fare and carrier rules apply to pets; trained service dogs travel under disability accommodations and DOT documentation rules, not the paid pet program. Confirm Southwest’s current service-animal process when you book.

Identity records vs. airline travel documents

Southwest’s pet program is an airline carriage policy. It is not a government-issued EU pet passport, UK PETS scheme document, or USDA endorsement. Separately, Animal Passport publishes a digital animal and livestock passport that uses muzzle biometrics (a nose print treated as unique like a fingerprint), phone-based capture that can bind owner, breed, estimated age, body condition, and vaccination history, age estimates from a dental photograph with a confidence score, and a body condition score of 1–5 from a side-profile photo. That product was used in livestock flood rescue in Pakistan (August 2025) so farmers could reclaim animals when paper tags washed away. It is not a Southwest boarding pass, not veterinary diagnosis, and not a legal substitute for airline or state entry paperwork. For more field and identity reporting, see the Animal Passport blogs.

Practical checklist before you fly

• Confirm the pet is a small domestic cat or dog, vaccinated, and at least eight weeks old (Southwest Pet Policy).
• Call to reserve a pet slot early—six carriers per flight is the Contract of Carriage default cap.
• Measure your soft-sided carrier against Southwest’s published maxima (15×10×10 for the Southwest-branded carrier; 18×10.5×10 for others).
• Budget $125 each way per carrier on mainland itineraries ($35 interisland Hawaii) and pay at the ticket counter.
• Avoid mainland–Hawaii and international routings with pets.
• Check destination state or Puerto Rico animal-health rules via USDA APHIS and your veterinarian.
• Plan bathroom breaks early—Southwest says it will not hold a flight for a pet relief stop.

Last updated September 25, 2026, by Animal Passport. Fees and policies change; verify on Southwest Airlines official pages and USDA APHIS before travel.