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Why are Stuff Sacks Round?

Why are manhole covers round?

I am completely serious about this. Why are stuff sacks round instead of block shaped?

For example, most of the backpacks I own have one large compartment that is rectangular in shape. Given this, wouldn’t it be more efficient to pack them using stuff sacks that were rectangular in shape instead of cylindrical? It seems like there would be less chance of wasting space that way.

I could also see this being important for bicycle campers and motorcyclists who use paniers for carry camping gear.

I seem to remember Granite Gear making rectangular, brick shaped stuff sacks a few years ago, but I don’t recall if any other manufacturers followed their lead. Here are some examples:

Have any of you found whether packing with block shaped stuff sacks is more efficient that cylindrical ones?

Are cylindrical shaped stuff sacks cheaper to manufacture or more robust than rectangular ones?

Inquiring minds want to know.


  1. because rolled up sleeping bags are round … tradition in other words

    do square bags really save that much space … you should test it out … compress the same bag with both a round and square sack

    on his run to the south pole Roald Amundsen was stuck with round boxes for some of his store … so being the effing the genius norwegians they were … they decided to break up some biscuits and powder, sew some bags that fit in those cracks and then stuff them as to not waste any space

    robert falcon scott did no such thing ….

  2. Love the block-shaped Granite Gear sacks, I've got a bunch of them. I find they "stack" inside my pack really nicely. Another I like about them is the zip that goes along the long edge of the sack – superlative access.

    I've seen a couple of Japanese knock-offs in the same design, but no major brands other than granite gear. The construction does seem to be a little more involved than the usual stuff sack, what with the zip and finished squaring to the ends.

  3. I don't use stuff sacks. I put my sleeping bag in a hefty trash bag and I keep my toiletries, headlamp, and any electronics in a freezer zip lock bag. All my electronics are also in sandwich ziplock bags that is then put in the freezer zip lock bag with my toiletries, just for the reassurance if I get caught in some bad weather.

  4. Could it be a manufacturing issue — easier to sew a cylinder than a square?

    Granite Gear is the only company I recall that is addressing this with other-shaped bags — including rounded bags designed to pack around bear canisters.

  5. I don't have an inside track on why mfrs continue to produce stuff sacs with a circular footprint, but I suspect it has to do with consumer expectations that just happen to be out of date. The image in my mind is of the rolled bedroll strapped to a pack in old photos. Just a thought…

  6. @Chris – you are one step ahead of us, as usual. I will have to give these a try this winter.

    @Brian – I still like stuff sacks for organizing gear and haven't gone the route of just using one big trash bag for everything. I'm not sure how well it would hold up to river fords and I'm chicken to try.

  7. I really prefer the square stuff sacks. I have made most of my own (great "how to" article at… ). It is much cheaper, allows me to custom-size the sack, and I like to have different colors to make it easier to quickly find what I am looking for.

  8. Wouldn't the benefit of square stuff sacks be negated by our backpacks being circular?

  9. Milton – the interior of my packs are mostly square, except for the bottoms, but it is a matter of degree.

  10. If you have a pack made of cuben fiber or Dyneema X then your pack should be waterproof, except for the parts that aren't made of those fabrics, like a roll top, like on the mountain laurel designs prophet(my pack). Last summer north of Yosemite I went to ford what appeared to be a slow moving shallow river that was very wide, as I got to the center of the river it got deep and I got carried down stream for a bit. Once I got to shore I definitely stopped for the day because I was sure all my gear got soaked, but all the stuff in the hefty bag was perfectly dry. Also have hiked through snow storms and rain and all my contents have stayed dried using the hefty bag and zip lock bag combo, never once has my gear in the hefty gotten wet. I failed to mention that I also put my clothes not worn in the hefty bag with my sleeping bag.

  11. Don't use stuff sacks and you don't need to worry about which kind works better. :-)

  12. Great question and one that I had thought about some time ago, but maybe not quite seriously enough to blog about it :-)

    As DripDry mentioned earlier, there is an excellent article on ThruHiker's website (link above) that gives step-by-step instructions on how to make your own stuff sacks.

    I've made several of my own now and all of them have square bottoms by using the technique shown on ThruHiker's website. The square base is excellent for helping the sacks stand up by themselves and perfect for putting gear with corners in because they fit naturally into the shape at the bottom.

    Here are some examples of the ones that I've made ( Even with a squared off bottom, the upper and tops of the stuff sacks tend to be more cylindrical in shape as you stuff more gear into them – that's unavoidable I think.

  13. Not using stuff sacks seems to be the in thing. Some folks claim their rucksacks keep their down bags all dry without them. I don't and like stuff sacks. POD ones at the moment and they seem to be round which is why your question is a good one?

  14. A cylinder will have a lower surface area (and therefore weight) to volume ratio than a rectangular solid. Not saying that's the reason, but it's possible.

  15. Have any of you found whether packing with block shaped stuff sacks is more efficient that cylindrical ones?

    Yes – I switched to the Granite Gear Air Space (no longer made unfortunately) and it is easier and a lot more convenient than round ones. I prefer the ones with the zipper on top – easy to find stuff. I also found I can carefully fold/roll either of my shelters in one of these, and carry it inside my pack. All in all I would not go back to the round ones.

    Are cylindrical shaped stuff sacks cheaper to manufacture or more robust than rectangular ones?

  16. I've always wondered why stuff sacks for things like sleeping bags etc are sized (and shaped) for minimal dimensions. I generally repack the items I want to keep dry in slightly oversized stuff sacks, then stuff them into the pack where they take the shape of the pack, rather than a solid object that inevitably leaves gaps etc. A trash bag works well for this too, but I don't trust a plastic bag not to rip and expose my items to water.

  17. The MYOG section of has a article on making a rectangular cross-section stuff sack.

    As for round versus rectangular. If you are packing stuff into a bag, it is going to become round — it is nature's way.

  18. @BrianGreen cool – I've always admired the projects at Maybe it's time to try rolling my own.

  19. Mile High Mountaineering (a new company) is making block compression sacks that fit perfectly in their backpacks to make the most use out of that room.

    They also integrated a stuff sack directly into the backpack to stuff a sleeping bag into; so you wont even need a stuff sack for that anymore!

  20. I can't find a web site for them and says that their packs won't be available until spring 2011.

  21. @Martin

    You use a pack liner to keep things dry. In essence, it's one big waterproof sack with minimal weight, rather than a bunch of unnecessary smaller ones.

  22. Cant say I ever gave the shape of compression sacks much thought. Yes, I can see that there would be spaces at the ends. That is where i stuff my socks and other small soft things. If they were shaped more like a loaf of bread there may be issues with sharper corners.

    Like the picture of the man hole cover. I do know why they are made round and not square or rectangular or some other shape. Maybe somewhat the same thought went into the in initial compression sack design, but, probably it uses less material and just costs less to make.

  23. Stuffed materials want to become round, look at a full trash bag, forcing material into a cube will require extra strength over a cylinder so you'll need a heavier stuff sack with a lot of seams, and corners will have little stuffed in them compared to the center. Of course this is for sleeping bags, clothes, tarps, etc. Experiment if you want but the physics and engineering are undeniable and I wouldn't waste my time and money.

  24. Manhole covers are round so they don't fall back into the hole. Standard Microsoft interview question.

  25. actually, I was surprised as to how much additional room I had in my pack after I switched to the Airspace sacks. As for stuff sacks vs pack liner, stuff sacks allow a bit more organization in the pack and in camp. More a personal choice I guess.

  26. I have made my own for years and they are worth their weight! They cost a fraction of manufactured stuff sack and I am convinced they weigh a lot less too because I use sil nylon and tiny cord locks AND I have a huge range of colors. I always make them square bottomed. The best part of making your own is you can make them the actual size you need. So break out all the ancient sewing machines hiding in grandma's attic. It is so worth making your own stuff sacks! Even if your results aren't great starting out they aren't hard to master and you will make up the cost in your mistakes by NOT buying another manufactured stuff sack.

    I am dying to make some in cuben fiber!

  27. Interesting to hear that the airspace bags helps create more space. My winter pack is a tight fit, so this might be a good season to test them out.

  28. The bottom line as to why Stuff Sacks are round is…it is cheaper and easier to make them that way…one continual sewing pattern around the bottom, and one up the side and then one to encase the drawstrings and your done..Think about how many more steps would be needed and material to make a square costs less in labor and materials for a round one…

  29. Hey guys,

    My name is Jeff Popp and I'm the owner of Mile High Mountaineering (we're a new pack company from Denver). Round shapes are a bit easier to stuff into, however, when it comes to space efficiency in a pack, round is terrible. That's why we make block shaped compression sacs that are cut in the exact same shape as our packs. This is a very efficient packing system and I'm surprised that more manufactures don't do this.

  30. Forget Stuff sacks, What I have been waiting for for nearly 40 years of hiking still has not been produced, a six inch wide, 3 inch deep frying pan with a dome lid and folding handles and another smaller pot with folding handles to fit inside with oz. or ml's markings are the side that can be read inside the pan and a cup with a lip that won't burn my lips that fits inside the frying pan and other pot made out of anything but Titanium. With this set up I can just about make anything I want to eat and maybe Bake biscuits too.

  31. We seem to make a lot of stuff sacks and I find the square bottom ones are faster to make than round bottomed sacks. In my pack, however, it seems that I jam stuff into little vacancies between larger items, so I’ve been making a bunch that are just envelopes, which are even faster to make and work nicely. Either way, I prefer sacks that are oversized, to conform to the inside of my pack.

    • I know this is an old thread, but since I’m an old guy, I thought I’d share. I still use round sacks for one simple reason: they come with the gear, so they’re free. (I did have to buy a couple of food sacks to rig a bear bag.) For anything that doesn’t come with a sack, there are Ziploc bags.

      Anyhow, round sacks work well, and do fill up all the space in the pack IF you follow one piece of advice from Colin Fletcher: avoid the too-small stuff sack. If the sack is too small, it will be a hard round rock that will leave empty spaces and holes. However, if you use a slightly larger sack, the item(s) inside will give you a moldable shape, and the empty spaces go away. I’m not talking about using a 12L stuff sack to hold a 3L load; I’m talking about a 4Lor 5L sack for a 3L load.

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