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Southwest Airlines publishes under-seat dimensions

Photo by Rob Speed

Photo by Rob Speed

Unlike other U.S. airlines, Southwest does not stipulate what size carrier it will accept for in-cabin pets. Instead, it has published the dimensions of the under-seat space available to travelers. Southwest has a fleet of Boeing 737s (the -300, -500 and -700 series), and apparently the same measurement applies to all of its planes.

Southwest’s under-seat dimensions are as follows:

  • Window Seat: 19″L x 14″W x 8.25″H
  • Middle Seat: 19″L x 19″W x 8.25″H
  • Aisle Seat: 19″L x 14″W x 8.25″H

I think this is a very sensible approach. You can look at these dimensions and really understand that an in-cabin carrier that’s 20″ long just won’t fit. You can test, at home, whether your carrier can flex enough to fit under an 8.25″ ceiling and still give your pet the headroom she needs. I hope more airlines follow Southwest’s lead!

A few months later I traveled on a Southwest 737 (-700 series) with a tape measure, and posted a follow-up message about choosing seats with an in-cabin dog on Southwest.


  • Kate

    5/22/2011-I flew yesterday on Southwest with my 14lb mini poodle in the Medium Sherpa bag with dimensions of18″ D x 11″ W x 10.5″ H I bought at Petsmart. It fit fine in the middle seat sideways and window seat long ways. I’m glad I returned the Large, it would have been too big. I flew on the 737-300 and 737-700. No issues at check in or with flight attendants. Southwest charges $75 each way.

  • Thanks so much for the report, Kate! It’s so helpful to hear what real live travelers (and travelers other than me!) are encountering.

  • Norma Rosenberg

    You are a life saver. I have been contemplating traveling with my dog who would not fit in a travel bag the size outlined by southwest. So good to find out that the Sherpa bag I purchased, returned, and will purchase again works. Thanks a million.

  • Sabrina

    I flew two years ago with my 20 lb dog in a large Sherpa carrier. I put the carrier under the seat long wise and opened the front half way and put a sweater over my lap and all was fine the entire flight. The bag fit fine. This year we are using the same buy my dog has gained 1 lb. I am a bit nervous. We made a dry run to the airport as we did last time to Southwest and asked the supervisor what she thought and took a while to think about but she said it should work. So I will keep my fingers crossed. My dog is about as big as you can get to fly under the seat.

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