Weight/size to fit in one airline seat

Thank you so much for all the wonderful information. I've been flying Southwest exclusively because I can buy the two seats but I have always been able to have one refunded. It's been a long time since I've been on any other airline. Maybe by September I'll be o.k.

I used to be able to always get a refund of my second seat because the flight was never full and they do that pretty quick but on my last flight they told me they have cut back flights so they will be full and this one was so no refund. They told me you can ask if this is a popular flight that will normally book up. I was leaving Seattle and was kind of upset because I bought two tickets right but they charged me for my thrid bag.... would you not think if the flight is full and I am not getting a refund then I should have had two bags per a ticket? Either way, I think you will do find because when i was around 340 I flew on Delta to Colorado from TN and was able to have one seat but the flight back I was pretty smushed and the guy next to me was pretty annoyed but did not say anything.

I used to be able to always get a refund of my second seat because the flight was never full and they do that pretty quick but on my last flight they told me they have cut back flights so they will be full and this one was so no refund. They told me you can ask if this is a popular flight that will normally book up. I was leaving Seattle and was kind of upset because I bought two tickets right but they charged me for my thrid bag.... would you not think if the flight is full and I am not getting a refund then I should have had two bags per a ticket? Either way, I think you will do find because when i was around 340 I flew on Delta to Colorado from TN and was able to have one seat but the flight back I was pretty smushed and the guy next to me was pretty annoyed but did not say anything

You'll fit.  No worries. Especially when you figure you'll be down even more in September!  You won't even need a seat belt extender by then!

 I was a size 24 at my largest, and I never needed an extender or an extra seat.  (My shoulders did pour over into the seats of my neighbors, though!)

September is a long way away in DS time--you'll be fine!

 I was a size 20 at my heaviest and never had a problem fitting into one seat and did not need an extender.  I think you will be just fine by September :)

 Since Southwest's fleet is almost exclusively Boeing 737-700's I can tell you that the seat width is 17 inches and as a general rule of thumb double that and you get the average men's waist size that would be "comfortable" in said seat. So in this case that magic size is 34.

Now, in real life, I would say that one can easily Triple that number and be livable in said seat. At my heaviest I had a size 52 waist and was able to fit into a standard coach seat on the 737, 757, and AA's workhorse the MD-80.  I wont say those who had to sit next to me were the most comfortable (usually my wife or one of my kids) but it was livable for all involved. Now that I am a size 32 I don't worry about the width but rather the padding of said seat as my bony butt hurts on long haul flights with sparsely padded seats. That's what the free blankets are for, extra seat padding!!!

I flew back in april probobally at around 240 or 250 and a size 24 and did not need an extender and fit in one seat and my firend said she was comfortable sitting next  me