Flying with your cat can be stressful. If you can avoid buying a new pet carrier for the trip, that’s one less thing you have to worry about. But is your cat carrier airline approved? I’ve researched the current dimensions and requirements for pet carriers across seven major airlines and the IATA, and here’s what I’ve found:
On average, airline-approved cat carriers must be within 18″ x 12″ x 9″ and in good condition. For your cat carrier to be airline approved, it needs to be escape-proof, have adequate ventilation, and it can’t be broken in any way.
In this article, I’ll take a closer look at specific pet carrier dimensions and requirements at each of the major airlines and help you determine if your cat carrier is airline approved.
Airline-Approved Cat Carrier Dimensions
If you’re getting ready to fly with your cat, you may not have to buy a new pet carrier. Instead, check to see if your current cat carrier is airline-approved.
If your cat is comfortable in their current carrier— meaning they can stand up, turn around, and lay down with plenty of room— then you may be able to use it to fly with your cat in-cabin. The most important thing after your cat’s comfort is making sure your pet carrier will fit under the seat in front of you on the plane.
To see if your pet carrier is airline-approved, start by measuring it to find its dimensions. The average airline approved pet carrier size is 18″ x 12″ x 9″ based on the following recommended maximum sizes from each airline:
| Maximum Hard-Sided Carrier Size | Maximum Soft-Sided Carrier Size | |
|---|---|---|
| Alaska Airline | 17" x 11" x 7.5" | 17" x 11" x 9.5" |
| American Airlines | 19" x 13" x 9" | 19" x 13" x 9" |
| Delta | 18" x 11" x 11" | 18" x 11" x 11" |
| Frontier | 18" x 14" x 8" | 18" x 14" x 8" |
| Southwest | 18.5" x 13.5" x 8.5" | 18.5" x 13.5" x 8.5" |
| Spirit | Not allowed | 18" x 14" x 9" |
| United | 17.5" x 12" x 7.5" | 18" x 11" x 11" |
The sizes listed above are the maximum recommended sizes according to each airline’s website. Still, you should contact your airline before your trip to verify the maximum size allowed on your flight. Some specific planes may have more or less space than the dimensions listed online.
Also, most airlines recommend soft-sided carriers for flying with your cat. Soft carriers are collapsible and more likely to fit under the seat in front of you. If your cat is more comfortable in a hard carrier, that’s also fine. Just make sure you call your airline ahead of time to verify the maximum hard carrier size allowed.
If you think your cat carrier may not be approved for your flight, check out my recommendations for the 6 best airline-approved cat carriers here.
Other Airline-Approved Cat Carrier Requirements
In addition to being small enough to fit underneath the seat in front of you, an airline-approved cat carrier must meet the following requirements:
- Your cat must be able to stand up, turn around, and lay down without touching the edge or top of the carrier
- There must be adequate ventilation on more than one side so your cat can breath
- It must be able to fully enclose your cat and be escape-proof (zippers or clasps on openings)
- The carrier can’t be broken in any way
- The carrier should be leakproof and contain absorbent bedding
These requirements are based on both individual airline policies and those outlined by the International Air Transport Association (IATA).
The IATA also provides a great reference to make sure your pet carrier is big enough to keep your cat comfortable during the flight:
Basically, your carrier should be a bit longer than the length of your pet, twice the width of your pet, and at least as tall as your pet plus a layer of absorbent bedding. Still, it can’t be bigger than the space beneath the seat in front of you on your flight.
You don’t necessarily have to get out a measuring tape and measure your cat to figure this out (my cats would never let this happen, anyway.) Instead, just make sure they can comfortably stand up, turn around, and lay down in the carrier. Then, actually measure the carrier itself to make sure it’s compliant with the airline you’re flying.
Some airlines may have additional requirements for your cat carrier, and I’ve outlined these requirements below. Still, be sure to call your airline to verify the maximum dimensions for your flight before you go. Some specific aircrafts have more or less space than others.
Alaska Airlines Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: 17″ x 11″ x 7.5″
Maximum Soft-Side Cat Carrier Size: 17″ x 11″ x 9.5″
Alaska Airlines is well-known for their pet-friendly travel policies. They allow passengers to travel with a maximum of two pet carriers on a flight, but you’ll have to purchase the seat beside yours on the plane for your second pet.
In addition to being within the dimensions listed above, Alaska Airlines has the following requirements for your cat carrier to be considered airline-approved:
- It must be clean and leak-proof with absorbent bedding made of material that safe and non-toxic to the animal
- The carrier must enclose the animal and be escape-proof
- The carrier must have adequate air ventilation
- It must also be free of tears, cracks or breaks
Before your flight, be sure to contact Alaska Airlines to verify the maximum dimensions of the pet carrier allowed on your flight. Some specific aircrafts have more or less room than others.
For more information on traveling with your cat via Alaska Airlines, visit the company’s website online.
American Airlines Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: 19″ x 13″ x 9″
Maximum Soft-Side Cat Carrier Size: 19″ x 13″ x 9″
American Airlines allows you to bring one pet carrier as a personal item. For regular mainline flights on American, your cat carrier can be no larger than 19″ x 13″ x 9″.
American Airlines also offers regional flights on American Eagle. If you’re flying American Eagle, the maximum pet carrier dimensions are 16″ x 12″ x 8″.
In addition to the dimensions listed above, American Airlines also has the following requirements for carry-on pets:
- Pets must be able to stand and sit erect, turn around normally and lie down in a natural position in their kennel without touching any side or the top of the container
- Non-collapsible kennels can’t exceed the underseat dimensions of any aircraft included in your journey. Please contact reservations to verify maximum dimensions
- Soft-sided collapsible kennels can be slightly larger but still need to fit under the seat without having to excessively collapse the kennel, must be secure, padded, made of water-repellant material and have nylon mesh ventilation on two or more sides.
Before your flight, be sure to contact American Airlines to double-check that your cat carrier is the right size. Some airplanes have less room than others.
For more information about flying with your cat on American Airlines, visit their website.
Delta Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: 18″ x 11″ x 11″
Maximum Soft-Side Cat Carrier Size: 18″ x 11″ x 11″
Delta is one of the few airlines that doesn’t give a solid answer on the maximum cat carrier size. Instead, Delta’s website states that maximum carry-on kennel dimensions are determined by your flight as the space under seats varies by aircraft. For this reason, it’s important to call Delta before your flight to ask about the maximum cat carrier size.
That being said, Delta does recommend a soft-sided kennel with maximum dimensions of 18″ x 11″ x 11″ since this fits most aircraft types.
In addition to ensuring that your cat carrier is the appropriate size, here are Delta’s carry-on kennel requirements:
- Your pet must be small enough to fit comfortably in a kennel without touching or protruding from the sides of the kennel and be able to move around
- The kennel must be leak-proof and have ventilation openings on three sides (four sides for international travel)
Know that your cat carrier will count as your one carry-on item for your flight. Still, you can bring one additional personal item on the plane with you.
To learn more about flying with your cat on Delta, check out these five things to know.
Frontier Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: 18″ x 14″ x 8″
Maximum Soft-Side Cat Carrier Size: 18″ x 14″ x 8″
When I fly domestically, I nearly always go with Frontier because of their low rates. We’ve flown with our cats on Frontier twice, and we thankfully had a good experience both times.
Frontier’s maximum dimensions for a pet container are 18″ x 14″ x 8″ in order to fit underneath the seat in front of you. In addition to being under this size, Frontier has the following rules regarding cat carriers:
- It must be large enough for your cat to stand, turn around, and lie down in a natural position
- While it’s not a requirement, Frontier recommends a soft-sided case
While Frontier’s website doesn’t mention calling ahead to verify that your cat carrier will fit on the aircraft for your flight, it never hurts to double-check.
To learn more about traveling with your cat via Frontier, visit the company’s website.
Southwest Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: 18.5″ x 13.5″ x 8.5″
Maximum Soft-Side Cat Carrier Size: 18.5″ x 13.5″ x 8.5″
Southwest allows you to bring one pet carrier in-cabin on your flight for an additional fee. Your carrier must be within the dimension listed above.
In addition to making sure your cat carrier fits underneath the seat in front of you, Southwest includes the following information about in-cabin cat carriers:
- Soft-sided and hard-sided carriers specifically designed as pet carriers are acceptable
- The carriers must be leak-proof and well ventilated
Southwest also offers their own official pet carrier ($58 at the time of writing) that’s completely compliant. However, any cat carrier meeting the requirements is considered airline approved by Southwest.
To learn more about flying Southwest with your cat, visit the company’s website.
Spirit Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: Not allowed
Maximum Soft-Side Cat Carrier Size: 18″ x 14″ x 9″
Spirit allows you to bring one cat carrier with you on your flight as a carry-on. Your cat carrier has to be within 18″ x 14″ x 9″.
In addition to making sure that your cat carrier will fit comfortably underneath the seat in front of you, Spirit has the following requirements:
- Your cat must be able to stand upright and move about freely in the carrier
- The combined weight of the pet and carrier may not exceed 40 pounds
- Only soft containers are allowed in the cabin, but not the type that allows the pet’s head to remain outside
As you can see, hard-sided carriers aren’t allowed on Spirit flights. If your cat carrier is hard-sided, it won’t be considered airline compliant by Spirit. You’ll need a soft-sided cat carrier for this flight.
For more information about flying with your cat on Spirit, visit the company’s website.
United Airlines Cat Carrier Requirements
Maximum Hard-Side Cat Carrier Size: 17.5″ x 12″ x 7.5″
Maximum Soft-Side Cat Carrier Size: 18″ x 11″ x 11″
United Airlines also allows you to fly with one in-cabin pet. If you want to bring a second one, you’ll have to pay for the seat next to yours on the flight.
For your cat carrier to be considered airline approved by United, it needs to be within the dimensions listed above.
United’s website doesn’t offer any additional requirements for your cat carrier, but still make sure that your cat can move around freely and that your carrier is properly ventilated.
For more information on traveling with your cat on United Airlines, visit the company’s website.
Final Thoughts
If you’re getting ready to fly with your cat, make sure that your cat carrier is airline-approved. You can do this by calling your airline and asking them about any requirements for your cat carrier on your upcoming flight.
The average size of an airline-approved cat carrier is 18″ x 12″ x 9″ but the specific dimensions vary by airline and sometimes even from plane to plane. For this reason, it’s important to contact your airline ahead of time.
Overall, airlines recommend that you travel with a soft-sided cat carrier as it’s more likely to comfortably fit underneath the seat in front of you during your flight. In the past, I’ve flown Frontier with my cats (all in soft-sided cases) and had a great experience.
Whether your carrier is hard-sided or soft-sided, proper ventilation and adequate space for your cat are priorities.
More Travel Tabby Content You May Enjoy:
- 6 Best Airline-Approved Carriers for Flying With Your Cat
- 8 Best Cat Carriers With Litter Box for Traveling Cats
- 6 Best Food and Water Bowls for Traveling With Cats