The Best US Airlines for Flying with a Cat (2026): Southwest vs. Delta vs. United vs. American
All four major US carriers allow cats in the cabin on eligible domestic routes. Here's which is best for your situation — fee, fleet, and booking compared.
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The short answer: Southwest is the best US airline for most cat owners flying eligible domestic routes — it is the cheapest, allows two small cats per carrier for one fee, and its all-737 fleet means no surprises about cabin class or aircraft-type restrictions. Delta, United, and American are viable alternatives if your route is Southwest-free, your card earns status on another carrier, or you need something Southwest doesn't serve.
What follows is the decision framework — which airline for which situation.
How the four US carriers compare
| Airline | In-cabin fee | Cats per carrier | Weight limit | How to book | Fee refundable? | Fleet note |
|---|---|---|---|---|---|---|
| Southwest | $125/carrier, one-way | Up to 2 small cats (same species) | None stated | Call only — 1-800-435-9792 | Yes | All-Boeing 737 — no widebody complications |
| Delta | $150/carrier, one-way (tickets issued on/after Apr 8, 2025) | 1 (exception: 2 same-breed, same-size cats aged 10wk–6mo) | None stated (cabin/aircraft exceptions exist) | Contact Delta Reservations (call) | Confirm at booking | Restrictions vary by cabin, seat, aircraft, and route — confirm with Delta |
| United | $150/carrier, one-way | 1 | None stated | Add on united.com or contact United | Confirm at booking | Confirm aircraft type and cabin class when booking |
| American | $150/carrier, one-way | 1 | None stated | Online or contact Reservations | No — non-refundable | American Eagle regional jets use smaller carrier dimensions; 777/787 Premium Cabin: not permitted |
All fees and policies are as of May 2026. Airline policies change — confirm directly before booking.
Southwest Airlines — the practical case
Southwest charges $125 per carrier, one-way, for domestic US mainland flights. It is the only major US carrier with a lower price point than the $150 charged by Delta, United, and American.
The more significant advantage for many readers is the two-cat rule. Southwest allows up to two small cats of the same species in a single carrier for one $125 fee. On Delta and United, one carrier means one cat — the economics are immediate: two cats on Southwest costs $125; two cats on Delta or United costs $300 (two separate carriers at $150 each — Delta's only shared-carrier exception applies to two same-breed, same-size pets aged 10 weeks to 6 months, not adult cats).
Southwest does not publish a combined cat-plus-carrier weight limit for standard domestic routes. The only test is whether the cat fits comfortably inside the carrier, can stand and move around, and whether the carrier fits under the seat. Staff apply a welfare check at check-in, not a scale. This is relevant for owners of larger domestic breeds — a Maine Coon that might exceed European cabin weight caps is not automatically ruled out on any major US carrier, though aircraft- and cabin-specific weight exceptions can exist; confirm with your airline when booking.
The all-Boeing 737 fleet is underrated as a practical benefit. Delta, United, and American operate widebody aircraft and regional jets, both of which introduce complications: Delta restricts pets from international Delta One and flat-bed cabins, and has specific row restrictions on A330 and B757 aircraft; American Eagle regional jets require smaller hard-sided carriers than American mainline. Southwest has no widebody aircraft, no flat-bed premium cabins, and no regional jet subsidiaries with different carrier dimension requirements. The carrier that fits Southwest's underfloor space works on every Southwest domestic flight.
One operational difference: Southwest does not allow pets to be added to reservations online. You must call Southwest Reservations at 1-800-I-FLY-SWA (1-800-435-9792), confirm a spot is available, and register your cat. Southwest limits in-cabin pets per flight — most third-party sources cite around six carriers, though Southwest itself only says space is limited and first-come, first-served. On popular routes during school holidays and summer travel, those spots fill weeks in advance. Call as soon as you have your own ticket booked.
The pet fare is paid at the airport ticket counter by credit card on the day of travel — not online. Southwest does not accept gift cards or LUV Vouchers for the pet fee.
If you cancel your trip, Southwest refunds the $125 pet fare.
If Southwest serves your route, check available flights at southwest.com — then call 1-800-I-FLY-SWA (1-800-435-9792) to reserve a pet spot before the limited allocation fills.
Related: For the full Southwest pet policy, booking steps, and carrier requirements, see our Southwest Airlines cat in cabin guide
Delta Airlines — when it makes sense
Delta charges $150 per carrier, one-way, for in-cabin pets on domestic routes — for tickets issued on or after April 8, 2025. One cat per carrier is the standard rule. Delta's policy allows a narrow exception: two pets of the same breed and size may share one carrier if they are between 10 weeks and 6 months old — an exception that applies to kittens travelling together, not adult cats. Confirm the exact conditions with Delta when booking.
Delta restricts in-cabin pets by cabin, seat, aircraft, and route. Delta's current consumer-facing table lists up to two pets in First Class and Domestic Business/Domestic Delta One, zero in International Business/International Delta One, and four in Main Cabin. Delta's agency policy also restricts pets from bulkhead, exit-row, no-stowage, flat-bed, Delta One, Delta Premium Select, and certain aircraft-specific seats (including specific rows on A330-200, A330-300, and centre seats on B757-200). Confirm the exact cabin, seat, and aircraft with Delta before booking.
Delta recommends a soft-sided carrier with maximum dimensions of 18 × 11 × 11 inches, as this fits most aircraft types.
Booking: Contact Delta Reservations to book a pet — Delta's policy page directs customers to call. Delta operates a first-come, first-served limit on in-cabin pets per flight; call as soon as your own ticket is booked.
Delta earns serious consideration if your route is not served by Southwest, if you hold Delta Medallion status and want to accumulate miles on your travel, or if the specific itinerary works significantly better on Delta's network.
Related: For the full Delta pet policy and booking walkthrough, see our Delta Airlines cat in cabin guide
United Airlines — the basics
United charges $150 per carrier, one-way, for in-cabin pets on domestic routes. One cat per carrier. United's fleet includes widebody aircraft on some domestic long-haul routes — confirm whether your specific aircraft type and cabin class permits in-cabin pets when booking.
You can add a pet during booking on united.com, or contact United to add one to an existing reservation. In-cabin pet spots are limited per flight — add your pet as early as possible on busy routes.
United is a straightforward option if your route works best on United's network or if you hold MileagePlus status. There is nothing operationally distinctive about United's cat policy relative to Delta at the same price point — the fleet composition and network coverage are what determine which of these two makes sense for a given trip.
Related: For the full United policy and booking steps, see our United Airlines cat guide
American Airlines — the regional jet caveat
American charges $150 per carrier, one-way, for in-cabin pets. One cat per carrier. The significant practical difference from Delta and United is the American Eagle regional jet dimension requirement.
American operates a large regional network through American Eagle (operated by Envoy Air, SkyWest, and PSA Airlines). The carrier dimensions accepted on American Eagle regional jets differ from mainline American aircraft — hard-sided carriers on American Eagle flights must be 16 × 12 × 8 inches, versus 19 × 13 × 9 inches on American mainline. (Soft-sided carriers at 18 × 11 × 11 inches are accepted on all American flights.) Before buying a hard-sided carrier for an American-operated trip, confirm which aircraft type operates your specific flight.
American's widebody aircraft (Boeing 777-200, 777-300ER, 787-8, 787-9, and Airbus A321XLR) do not permit in-cabin pets in the Premium Cabin due to lack of underseat storage. In-cabin pets are permitted in the main cabin on those aircraft, with a maximum of 20 pet carriers across all cabins on widebody flights.
American's pet fee is non-refundable. Pet spots are limited per flight; book early on busy routes.
Related: For the full American Airlines policy and booking walkthrough, see our American Airlines cat in cabin guide
Which airline for which situation
You have two cats travelling together: Southwest. Two small cats in one carrier for $125 — versus $300 on Delta or United (two carriers required for adult cats). There is no comparison.
Your cat is large (heavier breed, or over 8 kg): All four US carriers generally avoid the weight limits that European carriers impose (KLM, Lufthansa, and most EU airlines cap the combined cat-plus-carrier weight at around 8 kg). The four major US carriers generally do not publish a standard domestic in-cabin weight limit, though aircraft- and cabin-specific exceptions exist — confirm directly when booking. The test across all four is primarily whether the cat fits comfortably in the carrier and whether the carrier fits under the seat.
Your route is exclusively on one carrier’s network: The fee difference ($25 per carrier) is unlikely to override the constraint that only one carrier serves your city pair non-stop. If Delta, United, or American serves your route, compare fares on Expedia before committing.
You might need to cancel: Southwest refunds the pet fare when you cancel the reservation. American’s pet fee is non-refundable (confirmed from aa.com). Delta and United refund policies should be confirmed directly when booking.
You already have status on Delta, United, or American: The $25 premium per carrier is a small cost if you are earning elite miles or using a companion fare. For status holders, the pet fee difference is rarely the deciding factor.
You want the simplest carrier-buying decision: Southwest’s all-737 fleet means one carrier that meets Southwest’s underfloor dimensions works on every Southwest domestic flight. On Delta, United, and American, you need to verify aircraft type for your specific route — regional jets and widebody restrictions can change what’s permitted.
Carrier requirements across all four airlines
All four carriers require that the pet carrier fits under the seat in front of you and that the cat can stand, turn around, and move with ease. Both soft-sided and hard-sided carriers are accepted. The cat must remain inside the carrier for the entire flight — from gate to gate.
Carrier dimensions vary slightly between carriers and between aircraft types — confirm the current accepted dimensions with your airline when you book, and verify the aircraft type for your specific flight. Southwest does not publish exact dimensions on its policy page; third-party sources cite approximately 18.5 × 9.5 × 13.5 inches for 737 underfloor space.
For a full comparison of airline-approved soft-sided carriers with verified dimensions, see our airline-approved cat carrier guide. The Pecute soft-sided carrier works well on US domestic routes and fits within the Southwest underfloor dimensions.
Frequently asked questions
Which US airline is cheapest to fly with a cat?
Southwest, at $125 per carrier one-way as of May 2026. Delta, United, and American each charge $150 per carrier. For one cat travelling domestically, Southwest saves $25 per leg. For two small cats in one carrier, Southwest saves $175 per leg compared to Delta or United (which require a separate carrier per cat at $150 each).
Can I fly with two cats on a US domestic flight?
Yes, on Southwest — up to two small cats of the same species may travel in one carrier for one $125 fee. On Delta, United, and American, one carrier means one cat for adult cats. Delta has an exception for two same-breed, same-size pets aged 10 weeks to 6 months sharing one carrier (charged as one pet) — this applies to kittens, not adult cats. Confirm with Delta when booking.
Do US airlines have a weight limit for cats in the cabin?
The four major US carriers generally do not publish a standard domestic in-cabin weight limit — the primary test is that the cat fits comfortably in the carrier and the carrier fits under the seat. Aircraft- and cabin-specific weight exceptions can exist; confirm directly with your airline when booking. This contrasts with most European carriers, which impose an 8 kg combined cat-plus-carrier limit.
How do I add my cat to a Southwest Airlines reservation?
Call Southwest Reservations at 1-800-I-FLY-SWA (1-800-435-9792). Southwest does not allow pets to be added to bookings online. Space is limited — call as soon as you have booked your own ticket.
Is the pet fee refundable if I cancel my flight?
Southwest refunds the $125 pet fare when you cancel your reservation. American’s pet fee is non-refundable — confirmed from aa.com. Delta and United refund policies are not explicitly stated on their current pet policy pages — confirm directly when booking.
Are cats allowed on all US domestic flights?
No — in-cabin cat travel on all four airlines is subject to route, aircraft, and cabin restrictions. Southwest does not allow in-cabin pets on US mainland to Hawaii routes. Delta and American also exclude Hawaii, and both have additional destination and aircraft-specific restrictions. Confirm your specific route, aircraft type, and cabin class before booking.
What size carrier do US airlines accept for cats?
All four carriers require the carrier to fit under the seat in front of you and the cat to be able to stand, turn around, and move. Exact dimensions vary by airline and aircraft type. Southwest does not publish dimensions on its policy page; American Eagle regional jets have smaller dimension requirements than American mainline. Confirm the current dimensions with your airline when you call or book.
What to do next
Southwest is the default recommendation for most US domestic cat travel: lower fee, two-cat capacity, no widebody complications, refundable fare. Search Southwest flights at southwest.com — then call immediately to reserve a pet spot before the limited allocation fills.
If your route doesn’t serve Southwest, compare Delta, United, and American fares on Expedia — the $25 fee difference across a round trip is $50, so it’s worth checking whether route or schedule tips the balance.
For the per-airline deep dives: Southwest · Delta · United · American
For carrier buying: airline-approved cat carrier guide
Fees and policies verified from airline primary sources, May 2026. Airline policies change — confirm directly with your carrier before booking.