The other day, I bought a bunch of normal-price moving boxes. They come as one big cardboard unit which you bend in various ways. When assembled, they appear to be extremely strong and yet they are just folded cardboard -- no tape or any other kind of "mechanism" holding it together.

It freaks me out. I feel as if I should be taping them anyway on the bottom side. I don't believe that they can possibly work like this, even though I have lifted them up and walked around with them with lots of stuff in them to try it out. I keep feeling as if they will burst at any moment, and they probably will on the day when there's a bunch of scary strangers handling them when I'm moving. And then all my items will be crushed and scattered all over the street.

How is it possible that those boxes can have such a steady bottom just from folding two large and two small parts? It seems to my brain that it should not have any kind of support at all since nothing appears to be "locking it in place". Does it rely entirely on the walls pushing against each other or something?

And yeah, I had to watch several videos to realize how you are supposed to fold it. The instructions on the box itself are confusing to say the least.

I assume that this kind of box has been an international standard for many/several decades by now. It doesn't seem like a new invention at all.

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    $\begingroup$ "Normal-price moving boxes". Wouldn't a photo be really useful here? You're on an international site and you have no location information in your user profile so it's not possible to know what you're talking about. $\endgroup$ – Transistor Mar 27 at 17:15
  • $\begingroup$ Yes, it is possible if you fold it the correct way, as you've found out later through video instruction. I think you have bought the X-strong box, rather than common box that is only good for soft clothing. But even then, for precious items, I wouldn't trust the box without tape the bottom :) $\endgroup$ – r13 Mar 27 at 17:16

Depending on the design, these folded boxes are good for weights between 60 and 300 pounds.

The box is "locked in place" because paper or cardboard can not be stretched. The only way you can easy way to change its shape is to bend it, and you the only way you can bend a piece of paper is to shape it into a cylinder.

But you can't "bend" the bottom of a box into a cylinder, because the four sides prevent that from happening. Also the box can't "slide and unroll" past the pre-formed creases where it is folded.

It is very hard to tear paper or cardboard unless you start by damaging one of the edges. If you try to break a sheet of ordinary paper by pulling evenly on two opposite sides you will probably fail, because you aren't strong enough. The folded construction of the box means that there are no accessible edges that can be damaged.

Of course if some vandal stuck a knife through the box and cut a hole in it there is nothing to prevent that, but if somebody wanted to steal the contents it would be easier just to take the box without damaging it at all.

Tape doesn't add any real strength unless you completely cover the box with it, in which case you just made another box out of tape. In fact that is done in some packaging methods, such as "shrink wrapping" a stack of items onto a wooden pallet, where the total weight of the items (e.g. bricks) held together only by the shrink wrap maybe be a few tons.


Following the points alephzero made, assuming we have a box with a sturdy geometry, 50 kg divided between the 100 cm of the edge of a square bottom (25cmx25cm) that are hanging from vetical walls of the box is way bellow the ripping resistance of the sandwich cardboard.

Of course using good filler material helps a lot, be it old clothes or bubble plastic sheet.

I see fascinating thoughtful packaging in these days of online ordering. i bought a standard size Ebike and enjoyed the packaging so much i didn't take the bike out before i study the box.

  • $\begingroup$ We always like seeing efficient things - like efficient use of space :) $\endgroup$ – Solar Mike Mar 27 at 22:30

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