Southwest Airlines Pet Policy 2026: $125 Fee, Cabin Only

Southwest charges $125 each way to fly with a dog or cat in the cabin on domestic routes. No cargo, no checked pets, no international flights — cabin only.

The fee is one of the lower ones among major US airlines, and it's refundable if you cancel. But you can't book your pet online — you have to call. This guide covers carrier rules, the booking process, what happens at check-in, and the enforcement patterns that trip people up.

In-Cabin Travel

Southwest allows small vaccinated dogs and cats in the cabin on domestic flights for $125 each way per carrier. Pets must be at least 8 weeks old.

Your carrier goes under the seat in front of you. Southwest accepts both soft-sided and hard-sided carriers with these max dimensions:

• 18.5" (L) × 13.5" (W) × 9.5" (H) for third-party carriers
• 17" (L) × 10" (W) × 9.5" (H) for the Southwest branded carrier ($58 on their store)

Southwest has no official weight limit. The real test: your pet must be able to "stand up and move around the carrier with ease." This rule has been on the books for 20+ years, but enforcement varies wildly by airport and agent.

Each passenger gets one carrier. You can put two pets of the same species in one carrier — two cats or two dogs, not one of each. They both need to fit comfortably.

Per-flight limits: Most Southwest flights allow 6 pet carriers total. Spots are first-come, first-served — there's no way to check availability online, which is why calling early matters.

Seat restrictions: No exit rows, no bulkhead seats with pets. Southwest now has assigned seating, so you'll board with your assigned group — no more jockeying for position at the gate.

Your carrier counts as either your personal item or your carry-on. You can still bring one more bag — either a personal item or a regular carry-on, whichever the carrier didn't replace.

Species

Dogs and cats only. Both must be vaccinated and at least 8 weeks old. Unaccompanied minors cannot travel with a pet.

Cargo and Checked Pets

Southwest doesn't offer cargo or checked pet transport. Cabin is the only option. If your pet is too large to fit in a cabin carrier, you'll need a different airline — Alaska Airlines offers cargo at $200 each way.

Service Animals

Southwest accepts trained service dogs only — no emotional support animals, no therapy animals, no dogs in training. ESAs fly as regular pets in a carrier with the $125 fee.

Service dogs fly free in all cabin seats except exit rows. You'll need a completed DOT Service Animal Air Transportation Form — dated on or after the date you bought your ticket. Present it at the ticket counter or gate on travel day. A vest, harness, or ID card won't substitute for the form.

Service dogs must be leashed or harnessed at all times. They can sit at your feet or in your lap if they're no larger than a child under two. A bag with just service dog equipment (food, bowl, blanket) doesn't count toward your carry-on limit.

You can notify Southwest in advance through Manage Reservation online — but the form is still required in person on travel day.

Breed Restrictions

None. Southwest has no breed ban for cabin travel. They do note that flat-faced breeds — French Bulldogs, Pugs, Boston Terriers, Persian cats — "are more susceptible to complications during flight" due to compressed airways. It's an advisory, not a restriction. Your flat-faced dog or cat can still fly.

Required Documents

These are Southwest's rules — separate from what your destination may need.

Domestic flights: Southwest doesn't mention a health certificate for standard domestic flights. Show up with your pet in an approved carrier and a confirmed reservation.

Puerto Rico: You may need an interstate health certificate from a USDA-approved vet. Southwest links to USDA APHIS requirements for Puerto Rico travel — check before you go.

Hawaii (interisland only): Pets can fly between Hawaiian islands at $35 each way, but not to or from the mainland. Hawaii has its own quarantine and import rules — those apply regardless of the airline.

How to Book a Pet on Southwest

1. Book your flight first on southwest.com. You can't add a pet during online booking.
2. Call 1-800-435-9792 (800-I-FLY-SWA) to reserve a pet spot. This is the only way — the website and app don't support it. Call as soon as you book — only 6 spots per flight, and they fill quietly.
3. Pay the $125 fee at the airport counter with a credit card. You can't pay online, and you can't use Southwest gift cards, flight credits, or LUV Vouchers.
4. Check in at the counter. Staff will check the carrier and tag it.
5. At TSA security: Hold your pet and walk through the screening device. The carrier goes through the X-ray. Your pet stays in the carrier at all other times — gate area, boarding, the entire flight.
6. Board with your assigned group. Southwest switched to assigned seating — you'll sit in the seat shown on your boarding pass.

Tip

The $125 pet fare is refundable if you cancel your reservation. That's rare among US airlines — most pet fees are non-refundable.

Common Mistakes

What Travelers Say

We monitor recent traveler experiences through Reddit, BringFido reviews, and other sources. Here's what keeps coming up.

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On the stand-up rule:

"We have a 16-pound Havanese and have been flying with him for 7 years on Southwest with the same Sturdibag carrier. Most of the time it's not an issue. Flying back out of IAD the past few years, we get hassled each time about the carrier size and the fact that he can't stand in it. Most dogs over 10 pounds can't stand in a carrier under Southwest's height restriction." — Pimms, BringFido review

"I have an 18-lb pup that I've flown with a few times a year. In the past at check-in they haven't even inspected the carrier. This time they did and told me he was too big because he couldn't stand up." — landers329, Reddit

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On Denver enforcement:

"If I could give 0 bones for Southwest in Denver, I would. We've flown with our dogs 8 times without problems. This time the agent wouldn't let one of our dogs fly because he couldn't stand up and turn around — the same carrier we'd used all 8 times." — Elisabeth, BringFido review

"Denver specifically, some ticket agents have gotten very anal about the stand-up rule. I've never been questioned at any other airport." — Chartzilla, Reddit

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On carrier choice:

"The Away brand pet carrier fits beautifully under the middle seat on Southwest with no problems and no need to bend or force it to fit." — Reddit user, r/SouthwestAirlines

"Soft-sided carriers are the way to go. They flex and compress, which gives you a margin that hard-sided carriers don't." — Reddit community consensus

Watch Out

Denver is consistently the strictest airport for pet enforcement on Southwest. IAD (Dulles) is also flagged. Most other airports are more relaxed — but your experience depends entirely on the agent at check-in.

Tips for Flying Southwest with Your Pet

Use a soft-sided carrier. Hard-sided carriers have zero give. A soft-sided carrier like the Sherpa Original Deluxe or Sturdibag flexes enough to slide under the seat even if it's technically at the dimension limit. Most experienced Southwest pet flyers use soft carriers for this reason.

Keep old tags on your carrier. Southwest tags your carrier at check-in. Leave previous flights' tags attached — it signals to agents that your pet has flown before in that carrier and short-circuits the "is it going to fit?" inspection.

Call to book immediately after buying your ticket. Only about 6 pet spots per flight, no way to check online. Don't wait — spots fill without warning.

The hidden costs. The $125 fee is just the airline's cut. A carrier runs $30–$100 (the Sherpa Deluxe and Away Pet Carrier are popular with Southwest flyers). If you're flying to Puerto Rico, a health certificate from a USDA-accredited vet costs $150–$300. Budget the full picture.

Avoid Denver if you have a borderline pet. If your dog is 15+ pounds and can't fully stand in the carrier, Denver check-in is a gamble. Consider flying out of a different airport if you have the option — most other Southwest stations are more relaxed about enforcement.

How Southwest Compares

Southwest's $125 fee is now one of the lowest among major US airlines — Delta, United, and American all charge $150. The refundable pet fare is a genuine advantage — no other major US airline offers that. But the phone-only booking, no cargo option, and domestic-only restriction limit who Southwest works for. If your pet needs cargo, Alaska Airlines is the best domestic option at $100 cabin / $200 cargo.

FAQ

Your next step: Call 1-800-435-9792 to reserve your pet's spot — Southwest limits pets per flight and the spots fill without warning. Book the call the same day you buy your ticket.