lightweight packable backpack

I purchased the backpack you mentioned but it didn't fold down as much as I'd like. So I bught this one instead:

https://www.amazon.com/Sea-Summit-Ultra-SIL-Pack-Grey/dp/B0763N1VF5/ref=sr_1_3?crid=35JFYC5S0T78K&keywords=sea+to+summit+backpack&qid=1655839685&sprefix=sea+to+summit+backpac%2Caps%2C497&sr=8-3

I like it. It is very thin but seems sturdy. It folds down to the size smaller than a baseball.

Don't expect packable backpacks to have shape. If they did, they couldn't be packable.

I was going to say the smae thing as Frank re: packable and having shape.

But I would add that I think it's more space saving to leave the bags unpacked/unfolded and to just flatten them all the way down to a thin layer (or to use them like a packing cube / stuff sack inside your luggage). YMMV!

I use a waterproof running backpack that doesn't exist anymore :(

Is this going to a “personal item” you carry on in addition to a carry-on roller bag? If so, you should check the airline’s size requirement.on British Airways, for example, the size limit for a personal item is 16 x 12 x 8 inches, and I had to look around quite a bit to find a good daypack that was under 18” in height. They sometimes go around and check the dimensions in the boarding area.

I see that Amazon one you linked does not give dimensions. But I suppose with a soft collapsible pack like that it doesn’t matter as much, as you could just fill it halfway rather than fill it up for the plane, and it would squish down to fit in the sizer.

This pacable backpack by LLBean works wonders for me both on my trips and at home.
https://www.llbean.com/llb/shop/126140?page=llbean-stowaway-pack&csp=a&feat=86674-recs.dormantpdp

Another vote for the Sea to Summit, this thing really packs down to a small size yet you can get a lot in it once you expand it.

This one worked for us for short dayhikes or in the city. Compacts nicely to maybe a softball size.

https://www.amazon.com/gp/product/B00OISJYD4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Yet another vote for the Sea To Summit bags here. I don't have the backpack, but I have the duffel and the sling bags. The duffel has taken at least eight major trips with me over eight years, and it's still going strong. I have checked it numerous times on return flights, and it has always survived.

I have a different Sea to Summit bag I purchased at REI. It weighs 2.5 oz and stuffs into an attached sack that is about half the size of a baseball. I put the bottle in the bag. Like that is so lightweight. I used it to on a recent cities trip. It allowed me to use a lightweight purse and still carry other items easily.

I have a packable backpack from Eddie Bauer that I really like. I believe it’s 30L (I think they make a couple different sizes). I use it as my personal item on flights. It’s soft and squishable so I’ve never had trouble fitting it under the seat.

In addition to above responses, here’s a couple more. RS civita, osprey daylite tote pack, Patagonia lightweight tote pack.

I have used the Patagonia lightweight tote pack as an underseat bag on a few flights including frontier airlines. For a smaller pack - the RS civita. Do you want maximum underseat bag to carry 3 days worth of clothes (27 - 30 liter) or just flight comforts and necessities (15 - 20 liters)? There’s a big difference.

the kids at packhacker.com have plenty say about dozens of similar packs.Youmneed to do,a,bit of searching and they tend to have weirdly incompressible hipster prejudices.

I have a Eddie Bauer packable pack but never use it because the lack of a padded back makes it extremely uncomfortable.

A good alternative is the Osprey Daylite or Daylite Plus. It is not “packable” but is collapses flat enough that you can fit it in your suitcase with no problem.

G4 Free Packable. Used this last month. Highly recommend. I don't like that I've only been able to find it on Amazon and it's made in China but it a seriously good packable. I could shrink it down to nothing or expand it to a full 40 litres with outside pockets and spots for s-hooks if desperate. When I got home I bought more in case they stop selling them because I won't travel without one now.

I like this one. https://www.amazon.com/dp/B07K47BG6K?ref=ppx_yo2ov_dt_b_product_details&th=1

For me, an underseat is my entire baggage. I will put something more like the Zomake inside, for day-use during my trip. I've tried a few different things. I use them mainly to carry some extra warm clothing items, pack a picnic, laundry or carrying groceries from the grocery store.

The two favorites now are either a little fold up backpack I got at AAA or a grocery bag I bought at a Grocery Store in France. The AAA one folds smallest and weighs the least but it's nothing special as a backpack. Very little structure (even less than the Zomake). The grocery bag folds flat (then I'll fold in half again). It doesn't take up much space but it's not as tiny or light weight as the AAA bag. The two advantages of the grocery bag are it can hold heavy items and you look like a local carrying a grocery bag from a local store.