Airline pet carrier size checker

IATA’s formula gives inside dimensions. Airlines give the largest outside size that goes under the seat. A soft-sided carrier’s frame, mesh and base pad take up room, so a carrier built to an airline’s exact limit holds less than that inside. When the checker says IATA’s minimum is within a limit, it means the space your pet needs is smaller than the airline’s outside figure. It does not mean a particular carrier will do, so measure the one you have in mind, inside and out.

The checker sets one figure beside another. Choosing the carrier itself takes two decisions that neither figure makes for you: whether the airline wants a soft-sided one or a hard one, and which flight of the trip has the smallest limit.

6 of the airlines listed publish that a carrier in the cabin has to be soft-sided: Breeze Airways, Air Canada, Porter Airlines, Air Transat, Flair Airlines and PAL Airlines. Air Canada says, “The carrier must be soft-sided and flexible”. Air Transat says, “A hard-sided carrier or any other type of bag is not permitted”. 5 more publish a preference rather than a rule: American Airlines, Southwest Airlines, Frontier Airlines, Allegiant Air and Pacific Coastal Airlines. Allegiant prints both at once: “Soft-sided pet carriers are preferred (hard-sided carriers accepted)”.

Where an airline publishes a figure for each kind, the soft-sided one is not always the larger. American publishes 18 x 11 x 11 inches for a soft-sided carrier and 19 x 13 x 9 inches for a hard one on its mainline flights, longer and wider but two inches shorter. Frontier allows the same length and width either way and three more inches of height for a soft-sided container. Allegiant’s soft-sided figure is the larger on every measurement. So read the figure for the kind you are buying rather than the airline’s roomiest.

The second decision is the flight rather than the airline. American publishes 19 x 13 x 9 inches for a hard-sided carrier on its mainline flights and 16 x 12 x 8 inches on American Eagle flights, and Air North 18 L x 15 W x 9 H inches on its Boeing against 15 L x 11 W x 9 H inches on its ATR. A smaller aircraft is not always the tighter one, and Air Canada is the example: it publishes a larger size for its Dash 8, E175 and CRJ900 flights than for its Airbus and Boeing ones. American states the principle itself: “Non-collapsible kennels can’t exceed the under-seat dimensions of any aircraft included in your journey”. The size to buy for is the smallest one on the whole trip.

These pages publish what the carrier has to be as well, which is not a size and is not in the checker. Porter says, “The pet carrier must be leak proof and well ventilated”. Allegiant Air, Breeze Airways, Air Transat, Pacific Coastal Airlines and Pascan Aviation each ask for that pair in their own words. Delta puts a number on it: “The soft-sided kennel must be leak-proof and have ventilation openings on 3 sides for domestic travel and 4 sides for international travel”.

Southwest Airlines, Frontier Airlines, Air Canada, Porter Airlines, Air Transat and Pascan Aviation each want the animal able to stand up, turn around and lie down inside. And one carrier does not always hold one animal: JetBlue, Breeze Airways, Porter Airlines, PAL Airlines and Pacific Coastal Airlines publish a single pet to a carrier, where Southwest says one “can contain no more than two of the same species of small cat or dog”.

Each figure and each quotation here is from the airline’s own page, and the table below gives that page and the date it was read.

The checker lists 33 airlines, read on September 15 and 16, 2026. It holds a published cabin limit for 22 of them, a recommendation for one, and names the other 10 as not known, along with the reason.

United States: American Airlines, Delta Air Lines, United Airlines, Southwest Airlines, Alaska Airlines, Hawaiian Airlines, JetBlue, Spirit Airlines, Frontier Airlines, Allegiant Air, Sun Country Airlines, Breeze Airways, Avelo Airlines, Contour Airlines, Cape Air, Mokulele Airlines, Southern Airways Express and Advanced Air.

Canada: Air Canada, WestJet, Porter Airlines, Air Transat, Flair Airlines, PAL Airlines, Air North, Canadian North, Pacific Coastal Airlines, Calm Air, Central Mountain Air, Harbour Air, Air Inuit, Pascan Aviation and Air Creebec.

Canada’s regional and northern airlines each publish their own carrier size, and several differ from Air Canada’s and WestJet’s, which is why they are here. Flights sold under a larger airline’s regional name, such as American Eagle or Air Canada Express, are listed under that airline. PAL Airlines says its cabin pet policy does not apply on Air Borealis flights.

The list is not complete for either country. The figures are checked against each airline’s page every month, and a page can change between checks, so confirm the size with the airline when you book.

A pet over an airline’s cabin limit may be able to fly as checked baggage or as cargo, depending on the airline and the route, in a crate sized with the same IATA formula. Our airline crate size calculator works out IATA’s minimum inside dimensions for your dog or cat’s travel crate. The airline crate requirements guide covers what airlines ask of that crate, the crate size formula guide covers sizing it, and the pet shipping cost calculator covers what the move costs. If you would rather hand the planning to someone, our pet transport service can plan the route, the crate and the paperwork with you.

For more on a single airline, read the guides to American, Delta, United, JetBlue and Alaska, or the US airline pet policies guide. For Canada, the Canadian airline pet policies guide and the Air Canada and WestJet guides are on our Canadian site.