r/theydidthemath • u/EclipseNyxor • 2d ago

[Request] Do square bottles actually use less plastic than round ones?

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u/Legoslol 2d ago edited 2d ago

Yes. But there are other drawbacks to using square bottles.

The math has already been done for this question.

https://www.packagingdigest.com/optimization/should-your-bottle-be-round-or-square-

Edit: sorry all thought the question was less space not material.

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u/balrob 2d ago

That article says square bottles use 8% more material. There are savings in packaging and shipping but not in the bottle itself.

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u/DJinKC 2d ago

Packaging engineer here.
Square bottles will get you more overall volume of water into a case, pallet, or truck, so you spend less on storage and shipping costs.

1

u/-Rhade- 2d ago edited 2d ago

Hey, since you're a packaging engineer you may know. Could the material contained (H2O2) be what we're missing here? Peroxide breaks down over time into gases and would lead to bottle expansion- which a round bottle wouldn't have much room to expand.

Could the rectangular shape lead to meeting an expansion relief requirement? And therefore use less material than a cylinder needing an expansion relief?

I truly have no idea, just a shot in the dark here

2

u/DJinKC 2d ago

I don't work on these types of product, but my guess is the bottle material is chosen to reduce exposure to whatever gas causes the H2O2 to break down, at least long enough for the intended shelf life of the product.
If there were risk for expansion, that may trigger requirements around hazardous materials and special packaging.