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Update: Height of Southwest’s under-seat spaces (737 -300 and -700 series)

Back in September 2010, I reported that the height of Southwest’s under-seat spaces, at least on a 737 -700 series plane, was 11 inches. In December 2010, however, reader David alerted me that on his flight, the under-seat space was reduced to 8.5 inches by a life-vest container. I was surprised and concerned, but, happily, I had five Southwest flights scheduled for December and could check the situation out for myself. Here’s what I learned.

We flew on three 737 -700 series planes, and two 737 -300 series planes. The measurements I made on all of our flights turned out to be the same, so there were no differences in this regard between Southwest’s -300 and -700 series planes. The under-seat width measurements were the same as those I reported in my December 2009 post. Now for the height measurement: On every flight, there was a hard plastic container for a life vest that reduced the under-seat space height to 9-9.5 inches. However, that container is positioned pretty far forward — about 7 inches from the part of the seat closest to your knees. The container itself is about 7 inches wide, so it leaves some full-height space on either side of it.

Chloe's carrier, oriented left-to-right on our SEA to STL flight

Because we typically use a large SturdiBag for Chloe, oriented left-to-right, the hard plastic life vest container was no problem for us. Our SturdiBag (and I swear I am not affiliated in any way with the SturdiProducts company!) is rounded on top, besides being very flexible, so it never ran into the life vest container.

I am also not surprised to hear from reader Lizabeth that her pup Avery traveled comfortably under a Southwest seat in her Sleepypod Air carrier. The picture Lizabeth posted on Dog Jaunt’s Facebook page shows Avery’s carrier oriented front-to-back under the seat — which would work, even though the Sleepypod Air is 10.5 inches tall, because the life vest compartment is not perfectly centered (at least under the middle seat), and the top of the Air will deflect a bit to one side.

I can well imagine that a large, rigid rectangular carrier (and when I say “rigid,” I mean not only hard-sided carriers, which you don’t see much these days, but also soft-sided carriers with firm edges) more than 9 inches tall would have some troubles with Southwest’s under-seat spaces.

I’m left, of course, wondering whether the one plane I measured last September was the only one in the fleet not equipped with hard life vest containers (because yes, I did reach all the way under to feel for obstructions)! This is yet another example of the awesomeness of Dog Jaunt’s readers. My thanks to reader David, and to all of you, for helping to make Dog Jaunt a better, more useful blog.


  • Ha! Thank you! It turns out that people buy carriers and make travel plans and serious things like that, all based on my measurements — pretty motivating, I tell you what…

  • Peggy Felice

    Does anyone know what brand of carrier southwest airlines sells and what size?

  • Alex

    I love this site. We are attempting to take our mini schnauzer on his first flight in August from St Louis to Seattle (direct flight) and we are somewhat anxious to see whether everything will work out fine. We bought the XL SturdyBag carrier (the largest they sold) and while the length and width are fine, it is definitely taller than the official 8.25 in. Since it is flexible I hope that it will work though.

    Questiony: So you are certain that there are 9-9.5in room as opposed to the 8.25in? On the picture you provided the container for the life vest would be located to the left and right of the sturdibag, I assume? What is the hight next to the container for the life vest? Also, did you ever have trouble because of the size of your sturdybag? Who does officially check the size of your pet carrier?


  • Hi, Alex! The mini Schnauzers I’ve seen have been about Chloe’s size, so you should be just fine. We use the large SturdiBag, which is the one you see in the picture. The XL SturdiBag is darned large — the height won’t bother you, because it’s the same height as the large, which works for us, but the 20″ length means that you will not be able to orient it left-to-right, as I have in the picture. On to your questions: Yes, the height is 9-9.5 inches under the life jacket container. The container is a single box in the center of the space, but located deep under the seat, so that the SturdiBag, with its rounded top and oriented left-to-right, dodges it. The height next to the lifejacket box is 11 inches, as it is at the front of the space, closest to your knees. You may be able to squash your XL bag alongside the lifejacket box, but it will press significantly into the roof of your carrier. I would suggest using the large size instead, and orienting it left-to-right, as I did. I have had a couple of ticketing agents express concern about the large SturdiBag, but I was able to show both of them how much the bag flexes, and they let me by. (Also, two challenges out of the many dozens of flights we’ve taken is pretty good odds!) I hope this helps, and that your travels go smoothly!

  • Alex

    Hey Mary,

    Thanks for getting back to me! Just ordered the large carrier just to make sure. So with SW you do not need to bring any documentation for proof of vaccination, is that correct? Also, since you flew from/to St Louis, do you remember if there is a pet zone at the airport? It is our first time flying with a pet…

    Thanks again,

  • Hi, Alex! Let me know what you guys think of the SturdiBag when you’ve tried it out, and safe travels! Indeed, Southwest does not require a health certificate. I haven’t yet been to the St. Louis pet relief areas, but there are supposedly two: “The first is at the Main Terminal: Ticketing & Departures Level, outside exit MT-6, and the second is at East Terminal: Bag Claim Level, outside exit ET-15.” If you get a chance, take a picture and let me know how you get to the one you choose from the concourse you arrive on!

  • Alex

    Everything went well with the large SturdiBag. No problem whatsoever. Our MiniSchnauzer enjoyed the trip! Unfortunately I did not get to visit the relief areas in St Louis. But they are both located outsize the checkin zone. So you will need to visit them before you go through the screening or have to leave the area and be screened again!

  • That’s great news, Alex! I’m so glad the trip went well. Not to worry about St. Louis — someday I’ll get there, or you’ll pass through again.

  • Eric

    I’m taking a two hour flight in a few weeks to pick up my new puppy. She is going to be a bullmastiff puppy, so this will be her one and only flight because she will be a rather large dog! From what I have read online, the medium Sherpa has been a lot of people’s favorite choice. After much research, I ended up ordering Southwest’s own branded carrier online. It is almost two inches wider than the medium Sherpa and over an inch longer. Yes, its normal height is only 8.5″, but with the use of a zipper you can expand its height up to 10.5″ (which is about the same height as the medium Sherpa, and also all you can fit on Southwest anyways). It was only $48, and since it says Southwest on the side I know I won’t get any trouble. I’ll report back in a few weeks on how it went!

  • Eric

    I also forgot to compare the Southwest branded carrier against the Large Sturdibag. The Southwest bag is 1/2″ longer than the large Sturdibag, and over an inch wider. Once expanded, the Southwest carrier is still 1.5″ shorter than the Sturdibag, however, this is a moot point because you have to squish the Sturdibag down to fit under the seat.

    Also, the Southwest carrier is even wider than the Large Sherpa and almost the same length!

    I’m sure the Southwest carrier should not be the choice for frequent fliers, however, for a onetime pet flier like me it seems like the best bang for your buck!

  • Thanks so much, Eric, for the measurements and comparisons. I used to sneer at the Southwest carrier, back when its top didn’t expand upwards, but since then I don’t have so many rude things to say. You’re right, it’s REALLY WIDE, and its height, once the squish of the SturdiBag is taken into account, is comparable. I need to revisit my earlier posts and change my tune. Please do let me know what you think, after your flight!

  • Eric

    OK, so we made the big trip this last weekend to go pick op our 8 week old Bullmastiff puppy (who was already 15lbs!). We used the Southwest branded carrier, and I must say I would give it mixed reviews. I did compare to all the major brands, and it definitely is larger than the Sherpas and Sturdibags. The problem with the bag is that it is not sturdy. Its regular height is 8.5″, but it expands past 11″ high once you unzip the extendable part of the bag (Southwest’s website says it only expands to 10.5″ high, but it was a little taller than this.) The problem is the extra 2.5″ extension doesn’t stay up unless you hold it up. I ended up getting some cardboard and taping it inside the bag so it would stand at 11″ on its own. This worked pretty well. I think if I was a regular traveller with my small dog I might get a better brand. For me it worked great because I will never be able to travel with my Bullmastiff ever again because she will be too big!
    Also, Southwest was great. No one gave me any problems, and in fact, all of the employees wanted me to take out my pup to take pictures with. I would definitely recommend Southwest when flying with your dog.

  • I am so glad to hear how it went, Eric, and to get a user’s report on the Southwest bag — thank you so much! And I’m delighted that everything went well. I too have had only good dog travel experiences on Southwest. I know it depends, really, on the individuals you encounter, but so far they’ve been sweethearts.

  • Andee

    Ah ha! Thanks, Eric! I found your comment by googling “Southwest pet carrier modifications to make it stand up”, lol. You hadn’t posted last time I was here 😉 . I’ll give it a try!

  • Joel

    Just moved cross-country and flew with our two cats (sorry, no dogs) from RDU to OAK on Southwest. Did a lot of research on carriers and your website was an excellent resource – thank you for putting all of this together! Wanted to contribute our own experience.

    Initially bought two medium Sherpa carriers (the Delta approved version), which was fine for our 7 lb cat, but too small for our 15 lb-er. Ended up returning one and bought a large Sturdibag instead – and glad we paid the extra $$ for it – much better design even without being able to top load. Although not particularly happy about the trip, our big kitty was comfortable in the Sturdibag for the whole ride. I sat in the middle seat with the Sturdibag pushed in lengthwise with the back part smushed down a bit to fit (not sideways as shown above) with a couple of inches sticking out from under the seat. No problems from the attendants. We put the Sherpa bag under the window seat lengthwise on the first flight with no problem (again smushed down a little in the back), but on the second flight the box under the seat was close to the front so we turned the bag sideways which was not a problem. Never had any issues at the check-in/gates at RDU/PHX. Almost none of the passengers on the flights knew we had pets with us.

    Thanks again for the info you share on this site!

  • Lisa

    I was wondering, how big is Chloe? We have a King Charles too, but he is 22 pounds. The problem that I see with our dog Oliver is that he might be a little too tall to stand up in a South west bag. Do the airlines really look at that in great detail. He should be able to fit in a Southwest bag, but not stand up, I don’t believe. Also, why can’t you have a Southwest Bag at check in and have a much bigger bag that he can go in to while you are waiting the 1-2 hours u until your dog is ready for boarding, then put him in a smaller bag. Has anyone tried that?

  • Hi, Lisa! Another Dog Jaunt reader has sent me a great e-mail about modifying the Southwest bag so its lid can be held up during flight (to give your dog the maximum head room) after being allowed to flop flat while the bag is under the seat. I must pull up my socks and post that. However, even fully lifted, the lid on the Southwest bag is only 10.5″ high — which is pretty good, but not as tall as even the large SturdiBag, which is 12″ tall. Now then. The Southwest bag is broader than the large SturdiBag, so that might affect your decision, but Southwest agents have been known to look closely at traveling dogs — and to prevent a dog they deemed too large from boarding. A 22-lb. Cavalier may occupy more or less space, depending on how he carries his weight, but if he looks like he completely fills the Southwest bag, I’d think of alternatives — like the large SturdiBag (which Chloe, a 13 lb. Cavalier who stands 12″ tall at the shoulders, uses), or even the XL SturdiBag, depending on how well you handle potential or actual stress. (Do a search for XL SturdiBag on this site, and you’ll find a post and comment thread about the brave souls who have made it work for them and their dog — I’m not one of them, the large is as large as I can stand to go, but they’ve had success). You could carry a big bag like the XL SturdiBag, and give your dog a break in it during your waiting period (being discreet, and making sure your pup exits one bag straight into the other, preferably without anyone noticing), but two things: (1) If he needs the break, he probably also needs the bigger bag to fly in, esp. on a long flight, and (2) your trouble points are not during the waiting period but at the moments that you’re interacting with the ticketing agent and the gate agent — both times when your dog would be in the smaller bag. On balance, I’d suggest going for the large or XL SturdiBag (making sure that the bag you choose lets him at least turn around), rather than the Southwest bag. Let us know what you decide, and how it goes!

  • Adriana Ellis

    I was wondering if Lisa finally made it? I’m traveling with my 2 cavaliers in December and I’m still not sure if I should get the L or the XL Sturdi. Cooper is about 22lbs and Charlie about 16lbs. I’m pretty sure Charlie will be fine in the L but my main concern is Cooper.

  • Kurt

    Thanks for your help – I’m flying tonight (uh-oh!) with my 18lb 10 week old Rhodesian Ridgeback puppy who is slightly too large, maybe 12″ at the shoulder. I bought several bags to test and I have to say the Large Sturdibag won out by a long shot, I’ve only had him for a week and he hates his crate but I leave the Sturdibag open on the living room floor and he crawls in to take naps sometimes. If nothing else your site helped me get over some of the anxiety, and I printed a few pictures to show any agents that give me a hard time. So thanks very much!

  • Carolyn Karr

    I will be traveling from Atlanta to Seattle soon, I called the airlines and asked them if I am required to bring a health certificate for my puppy and I was told that they didn’t require one.
    I also asked if I DIDN’T bring a certificate with me and IF they wouldn’t let me board the plane because I didn’t get a certificate and I was told that it might be a good idea to get one in case they denied my pet to board.

    Help!!! Should I get a certificate or not?? What do you think??

    ps…I was told by a friend to get in touch with the USDA and they told me that I DID have to have a certificate.

    Many thanks,

  • Hi, Carolyn — Here’s my post about interstate health certificates: You’ll have to decide for yourself, of course, but I can’t remember the last time I got a health certificate for Chloe, traveling within the U.S. The only reason I can think of for anyone to prevent you from boarding with your pet is if a ticketing/gate agent decides she’s too big for the available space, or is so obviously, desperately ill (which they’d have to notice, somehow, through the mesh of her carrier) that she poses some kind of health threat. Whenever an issue with Chloe’s carrier has arisen, we’ve been able to talk our way past it — and the health certificate issue has never come into play at all. It’s always been about carrier size, or overall weight. And you simply don’t sound like an owner who would travel with a desperately ill pet!

  • Stephanie

    Hi, I will be starting regular travel between phoenix and portland oregon with my 18lb border terrier Ollie. I have not traveled with him in a few years, and the last time I did, the gate agent wanted to see him in his travel carrier, stand up and turn around. He doesn’t like being in it, so he presses every part of himself against the sides and looks like baby hughey stuffed into a tiny bag! She let me pass, but wasn’t pleased, so I’m nervous. I now have a large Sherpa bag that measures 18″ x12″x12″ high. From what I can find of airlines that fly that route, it looks like Alaska Airlines has the largest dimension under the middle seat in coach (18-20″x18″x11″tall?) Anyone have an experience with a “larger” dog on Alaska, Southwest, US Airways or? Also wondering how Lisa did with her 22lb King Charles back in June? Thanks!!

  • Ions


    Thank you so much for your awesome blog entries. They were really helpful and I’m thinking of buying the either the small or large SturdiBag (can’t seem to find any mediums) for my maltese that weights approximately 12 pounds. I haven’t measure him yet, but will do that as soon as I wake up tomorrow (it’s 230 am and I’m so obsess into finding the best pet carrier that I can’t even sleep).

    Also, have you been on Southwest flights recently? I’m flying for the first time with my pet on Southwest next month and I’m extremely nervous about the 8.25 height limit. It just seems impossible that any dog will be 8.25 inches high! Will the sturdibag give me any issues or does it really squish? Would you mind putting Chloe’s dimension so I can use it as a guide?

    Any advice on what to do if the ticket counter gives me a problem?


  • Hello, Ions — I’m so sorry for my delay in responding! We fly a great deal on Southwest, and we typically use the large SturdiBag for our 13-lb. dog (you’re right, there’s no medium). It squishes like a champ, and we have never had any issues with it. Chloe is 13 lbs., as I mentioned, and she’s 12″ at the shoulder. She’s about 16″ long from nape of neck to base of tail. My advice is to keep your pup’s carrier at your feet. Tell the ticketing agent you need to pay for your in-cabin pet. When she asks to see his carrier, lift him up without grunting, or indicating in any way that it’s an effort. Be calm and cheerful — convey the impression that you do this all the time, and it’s no problem at all. If there’s any concern, demonstrate how much the top flexes, tell them how comfortably he’s traveled before (a stretch, yes, but the fact is that Chloe has traveled comfortably many dozens of times on Southwest, and she’s a little larger than your pup). There are pictures on the blog of the bag in place on various planes, including many Southwest flights (look in the sidebar for the link) — show them those, if need be. Be of good cheer, and good luck! I suspect you guys will sail through.

  • Ions

    Thank you so much for your advice. Do you have any experience with dealing with Emotional Support Dogs?

  • I’m sorry, Ions, I don’t. You might want to contact the bloggers Gigi Griffis (she writes The Ramble) and Montecristo Travels — their pups are ESA, and they might be able to answer questions you have.

  • Ryan

    Hello, I wanted to know if you have any known people to get rejected on Southwest using the Medium Sherpa? I know it is not GOB (for some reason), but everyone seems to say that Southwest is flexible since the top will need to be pushed down. Thanks!

  • Hello, Ryan! I never have — if your dog fits comfortably in a medium Sherpa, it should be a shoo-in to get her onto a Southwest plane (and to fit the carrier under the seat). The only hitch would be if your dog appears to be squished in there, and a Southwest rep notices (and of course you wouldn’t want that either, being a loving pet owner).

  • Diane

    I flew SW with my Ragdoll cat. We use a Lg. Sturdy bag. 3 flights were no problem. However our last flight returning home from Portland, our 11 lb cat chewed thru the zipper material & almost escaped into the cabin. We had to put him in with our other Ragdoll . Any advice? We have size Lg. Because our kitties are quite large when mature…as much as 20+ lbs.

  • Holy smokes, Diane! I’m so sorry for my delay in responding, but maybe it’s just as well, because now I’ve traveled with a different bag that might work for you. Take a look at the Teafco Argo Petagon in the large size — it’d hold a 20 lb. cat, and the zippers are on the top, so less accessible — and the mesh is double-layer, and the inner layer is so fine that I think cat claws would have a tough time getting engaged enough to cause damage. Hope that helps!

  • Haleigh

    Hi Mary-Alice! I have a quick question, do you know if the underseat sizes for Southwest 737-300 series have changed at all? Lol only reason I wondered is because I have a carry on suitcase with the dimensions of (18″L x 15″W x 9.1 H” and wasn’t sure if that would be able to fit underneath a seat or if I’d have to put it in an upper compartment. 🙂

  • I don’t know, Haleigh! I should get my tape measure out again. I haven’t noticed a change in our experience of stowing Chloe, but I can’t back that up with inches.

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