Airline Pet Policy
Southwest has the simplest pet policy of any major US airline, and also the most limited. Small cats and dogs fly in the cabin for one flat fee each way, with no cargo hold, no checked pets, and no international routes. If your pet fits under the seat, you are set in a phone call. If it does not, there is no workaround at any price, because Southwest simply does not carry animals any other way.
In this guide
Southwest Airlines lets small vaccinated cats and dogs fly in the cabin on domestic flights, as long as the pet fits in an approved carrier that slides under the seat in front of you. The pet has to be at least 8 weeks old, and the fee is $125 each way per carrier on the US mainland. Only six pet carriers are allowed per flight, so you reserve by phone rather than at the gate.
There is no second option. Southwest does not fly pets in cargo or as checked baggage, and it does not carry them on any international route or to and from mainland Hawaii. For most travelers the policy reads as one clean rule: a small dog or cat under the seat, or no pet at all.
Only cats and dogs. Southwest does not carry rabbits, birds, or any exotic species as pets. If you have anything other than a small cat or dog, Southwest is not an option and you are looking at a different airline.
The headline number is $125 each way for a cabin pet, charged per carrier and per direction of travel, so a round trip runs about $250. That fee recently went up from the old $95 figure, so older guides still quoting $95 are out of date. Flights between the Hawaiian islands are the one cheaper case.
| Travel type | Fee | Notes |
|---|---|---|
| In-cabin, US mainland | $125 each way, per carrier | Round trip about $250 |
| In-cabin, between Hawaiian islands | $35 each way, per carrier | Interisland only, not mainland Hawaii |
| Cargo or checked pet | Not offered | Southwest does not fly pets in the hold |
How you pay matters. The pet fare is paid at the airport ticket counter, not during online booking, and it has to go on a credit card. You cannot use a Southwest gift card, flight credit, or LUV Voucher for it. The good news is the fare is refundable if you cancel.
On Southwest the carrier is the whole policy, because there is no weight class or cargo tier behind it. If the carrier fits under the seat with your pet comfortable inside, you fly. If it does not, you do not. Southwest flies a single family of Boeing 737 aircraft, so the under-seat space is consistent, and it is lower than many people expect.
| Requirement | Detail |
|---|---|
| Pets accepted | Small vaccinated domestic cats and dogs only |
| Minimum age | 8 weeks |
| Maximum carrier size | About 18.5 x 8.5 x 13.5 in (L x H x W) |
| Carrier type | Soft or hard sided, leak-proof, well ventilated |
| Weight limit | No published limit, the under-seat fit is the real constraint |
| Per carrier | Up to 2 pets of the same species |
| Per passenger | 1 carrier |
| Per flight | Up to 6 carriers, first come first served |
Your pet needs to be able to stand up and turn around inside the carrier. A soft-sided bag is the safer choice because it compresses into the low space under a 737 seat, where a rigid case can measure fine on paper and still not fit. The carrier counts as your carry-on or personal item, so plan the rest of your bags around it.
No breed ban, only a size limit. Unlike airlines that bar snub-nosed breeds from cargo, Southwest publishes no breed restriction, because there is no cargo hold to restrict. A French Bulldog or Pug can fly if it fits an approved under-seat carrier. The only question Southwest asks is whether the animal fits, not what it is.
This is the single most important thing to understand before you book, and it is where Southwest differs sharply from the legacy carriers. Most airline pet policies have three lanes: in-cabin, checked baggage, and cargo. Southwest has one.
Southwest accepts pets in the passenger cabin and nowhere else. There is no cargo booking line and no checked-pet service, so there is no temperature embargo to track and no crate rules to learn, because none of that exists here. The trade-off is blunt. If your dog is too big to ride under the seat in an approved carrier, Southwest cannot fly it under any circumstance, at any price. There is no upgrade and no exception.
The upside is real for owners of genuinely small animals. An in-cabin-only policy means your pet stays with you in the climate-controlled cabin the whole flight and never rides in a hold. If your pet is too large, though, you need a cargo-capable airline like the Delta pet policy or the American Airlines pet policy, or professional ground transport.
Southwest limits pets to domestic itineraries, and the geographic bans catch owners out mid-booking more than anything else in the policy. Here is the full map of where a cabin pet can and cannot go.
| Route | Cabin pet allowed? |
|---|---|
| Flights within the 48 contiguous US states | Yes, $125 each way |
| Between the Hawaiian islands | Yes, $35 each way |
| To or from mainland Hawaii | No |
| Any international flight (Mexico, Caribbean, Central America) | No |
| Puerto Rico | Yes, with health documents |
The international ban is absolute. It does not matter if the route is a short hop to Cancún or the Caribbean. If the plane crosses an international border, pets cannot board, in the cabin or anywhere else, because Southwest has no live-animal cargo division to fall back on.
Hawaii is the one place where the rules split. You cannot fly a pet to or from mainland Hawaii on Southwest, so a flight between, say, California and Honolulu is off the table for your dog or cat. You can fly a pet between the Hawaiian islands, and the interisland fee is the lower $35 each way. The reason is regulatory. Hawaii runs a strict rabies-quarantine and animal-import program through the Hawaii Department of Agriculture, and Southwest stays out of it by not carrying pets on mainland Hawaii routes at all.
Pets can fly to Puerto Rico, but the destination adds paperwork. You will generally need an interstate health certificate from a USDA-accredited vet and proof of rabies vaccination before entry. Our entry rules guides cover the specific requirements, which Southwest itself does not handle for you.
Once you are on the plane the rules are simple and strictly enforced. The carrier stays on the floor, under the seat in front of you, for the entire flight, including taxi, takeoff, and landing.
Disruptive pets can be denied boarding. A pet that will not settle, that shows aggression, or that cannot stay quiet in its carrier can be refused at the gate. Acclimate your pet to the carrier well before travel day, because the gate is a bad place to find out it panics.
What you need on paper depends entirely on where you are flying. For most Southwest trips, which are mainland-to-mainland, the answer is very little.
Southwest does not require a health certificate for a cabin pet flying between US mainland cities. It is still smart to travel with a recent certificate from your vet in case a connecting situation or destination asks for one, but Southwest agents will not demand it at the counter for a standard domestic flight.
Puerto Rico is the exception. Travelers bringing a pet generally need an interstate health certificate from a USDA-accredited vet and proof of rabies vaccination. Sort this out before travel day, because it is a document you cannot produce at the airport if you have not already arranged it.
The airline and the destination are separate gates. Southwest's pet policy decides whether your animal gets on the plane. The destination's rules, like Puerto Rico's or Hawaii's, decide whether it is allowed off at the other end. Clear both, because meeting one does not mean you have met the other.
This is where the rules changed most, and where a lot of older advice online is simply wrong now. Since the 2021 update to federal air travel rules, the two categories are treated very differently.
If your animal provides comfort rather than trained tasks, plan and budget as a pet owner, not as a service animal handler.
You cannot add a pet online, and you cannot just show up with a carrier. Spots are capped at six per flight and go first-come, so booking the pet is a separate step from booking your seat.
The Southwest pet fare is $125 each way, per carrier, on US mainland flights, so a round trip is about $250. Between the Hawaiian islands the fee drops to $35 each way. You pay it at the airport ticket counter, not during online booking, and it has to go on a credit card, not a gift card, flight credit, or LUV Voucher. The fare is refundable if you cancel.
No. Southwest carries pets in the cabin only. There is no cargo service and no checked-pet option, so a cat or dog that does not fit under the seat in an approved carrier cannot fly on Southwest at any price. If your pet is too big, you need a cargo-capable airline like Delta or American, or professional ground transport.
No. Pets are allowed on domestic itineraries only. If any leg of your trip crosses an international border, including short hops to Mexico, the Caribbean, or Central America, pets are not permitted. Southwest also bans pet travel to or from mainland Hawaii, though pets are allowed on flights between the Hawaiian islands.
The carrier must fit fully under the seat in front of you, with a maximum size of about 18.5 x 8.5 x 13.5 inches. Soft or hard sided carriers are both accepted, but they must be leak-proof and well ventilated, and a soft-sided bag is the safer bet because it compresses under the low Boeing 737 seat. Your pet has to be able to stand up and turn around inside.
Book your own ticket first, then call Southwest at 1-800-I-FLY-SWA (1-800-435-9792) to add the pet, because you cannot do it online. Only six pet carriers are allowed per flight on a first-come basis, so reserve early. On travel day you check in at the ticket counter, where an agent inspects the carrier, and you pay the fee there.
No. Since the 2021 change to federal air travel rules, Southwest treats emotional support animals as pets. They pay the standard $125 fee and follow every pet rule. Only fully trained service dogs fly free in the cabin, with the DOT Service Animal Air Transportation form submitted ahead of travel.
Information on this page reflects the Southwest Airlines pet policy as of July 2026. The pet fare, carrier sizes, allowed routes, and booking rules are set by Southwest Airlines and change over time, and destination entry rules for places like Puerto Rico and Hawaii are set by the relevant agencies. Always confirm current requirements with Southwest Airlines at southwest.com before you book.
Southwest is the simplest option for a small pet, but useless for a large dog and any international trip. Fees, cabin limits, and cargo rules vary a lot by airline. Compare who will take your dog or cat on your route before you lock in dates.
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