Why are aluminium soda cans typically round instead of square?

  • Why are beverage cans usually round? Considering the amount that are made, and the need to be transported - isn't a round design inefficient? (ie the lost space from not tightly fitting together).

    Is there a usability impact on a round can vs a squared can for one handed drinking use?

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    There is a related question here but I believe the physical properties of aluminium mean there is a difference here.

    Well, they're easier to hold, for one thing.

    In addition to weak points at the corners, a square can would need significantly thicker walls to prevent them bulging out due to the pressure contained by the can. Even an uncarbonated beverage would probably cause noticeable bulging in a square can over a period of time.

    Did you do any research on this before posting this question?

    You say these cans are *usually* and *typically* round, but I've never seen non-round cans in my life. Could anyone link some images?

    Wouldn't a square "can" become a box?

    Is this really a UX question? Seems more of an engineering question. Kind of like the ones discussed here: What's the deal with “what's the deal with X” questions?

    There's a matter of timing and feasibility to consider also. Soda was invented in the 1780s, vending machines came along in the 1920s and 30s. Designing a package that could be easily machine handled was paramount to growing the business. Using the round can design, relatively inexpensive vending machines could drop and roll a fairly robust product with little worry that it would break. And have you seen vendors handling their product? They don't have to be careful - the can is just that good.

    Can't believe this question gets so much attention ...

  • It is a combination of manufacturing and usability... but mostly manufacturing.

    Doing a quick web search for "why are soda cans round" (Google does a decent job) yields multiple insights in the issue. But the only result you need to visit is engineerguy's YouTube video (you should also be Subscribed to engineerguy, because he is awesome).

    The Ingenious Design of the Aluminum Beverage Can

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    The answer of why a soda can is shaped the way it is is answered in the first 1 minute and 40 seconds.

    3 options are explored:



    • Uses the least amount of material
    • No corners, so no weak points when under pressure


    • Difficult to manufacture
    • Rolls off the table (a usability point)
    • When packed together, only 74% of volume is taken up by product



    • Sits on the table
    • Easier to manufacture


    • Awkward to drink from (a usability point)
    • Edges are weak points, requiring thick walls



    • Elements of both shapes
    • 91% of packing space used by product
    • Round shapes can maintain itself under the pressure of its contents (both inward and outward pressure)
    • Can be easily held (there's the usability answer)

    The density of optimal packing isn't really relevant if it's not used. I'm not familar with cans, but bottles are usually packed in a square formation, not in a hexagonal formation, reducing the density to 78% (pi/4).

    That video was awesome. Now I want to know why beans don't come in nitrogen-pressured beverage cans.

    @CodesInChaos cans are often packed in hexagonal arrangement. See, e.g.: http://pacepalletservices.com.au/wp-content/uploads/2012/12/amcor_block_pallets.jpg

    @CodesInChaos Perhaps it has something to do with once the cans are placed inside a box? If the cans were in a hexagonal formation and then inside consumer boxes (like a 12-pack) it seems like there would be more appreciable spaces between the inset cans and the box wall - creating weak/crush spots if stacked inappropriately.

    Most cases of soda pop cans in stores I've seen (USA/Canada) are packed in a "square" formation, similar to bottles but with no cardboard separators. Even big flats of 36 (like at Costco) are square packed, though they usually end up a little squished & kind of "hexagonal" packed, just from picking them up by the sides only, kind of like this image http://www.ezorder.com.sa/Images/Products/OM9103.jpg.

    +1 for mostly manufacturing. These cans can be turned from an aluminum die in seconds, while a square one would have to be stamped from a sheet, and very carefully to prevent tearings.

    Not mentioned: Sphere-Con: also awkward to drink from.

    Is a cuboid really awkward to drink from? The first thing I'd do with that design would be to move the drinking whole to a corner. (That) Problem solved.

    You forgot to mention that the cuboid uses roughly 100%of packing space for actual product.

    I don't see how *Elements of both shapes* is a *Pro* for *Cylinder*. I could also say a cylinder neither uses the space perfectly, nor minimizes the material and therefore combines the disadvantages of a sphere and a cuboid without combining the advantages.

    @nwp strong confirmation bias at work here. Cylinder has no cons.

    @Mindwin indeed, weakness to the sides, rolls in one orientation, easily compressed when not pressurised. I'm sure there's more I'm not thinking of.

    Let's not forget that sharp corners and metal doesn't equal a pleasant outcome for your hands. I've tore fingers and hands on sharp edges before!

    @CodesInChaos isn't it though? You design something with the idea that it will be used in a certain way and that way might be the most natural, user friendly way possible. If the user decides to use it differently, is that your failure as a designer or is it the user's failure to use the thing optimally?

    On hex vs. square packing: if you have to put the hexagonal-packed cylinders into a small rectangular box, you have to leave some space at the end of each row, and that eats some of your savings. The gaps could have other issues: maybe cardboard boxes or plastic wrap are more prone to getting crushed or torn around those big spaces with no can behind them reinforcing them. So space savings from hex packing could plausibly be worth it for the pallet in your picture but not for, say 24-pack boxes.

    A few percent more density also might just not matter much if your cost is mostly determined by weight (or other stuff), not volume. A case of drinks is pretty dense already vs., say, the average Amazon box I get, so that seems kinda plausible to me. Total speculation from just some random dude, obviously

    @twotwo Another advantage of the square packing: it's easy to see exactly how many cans are in a tray. You just multiply the number of cans on each side. A bit more difficult with the hexagonal packing.

    The pros-cons list for the cylinder and cuboid should mention: cube: optimal packing (pro), cylinder: good use of material (better than cube, worse than sphere)

    Saw this question; immediately thought of the video you linked; saw it's already here; upvoted. I can't think of any better explanation!

    That video is so well-made it could be a standard for how videos should be like.

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Content dated before 7/24/2021 11:53 AM