Wouldn’t it make more sense to have the cup be a consistent width throughout? Or, even make the cup wider at the bottom to make it more stable when sitting on a surface?
In: Engineering
When molding plastic it helps to have a “draft” or an angle, so when you pull the 2 halves of the molding tool apart, they separate easily without rubbing on the part being made, like the Cup. It simplifies the tooling and reduces the amount of time per mold cycle by speeding up the release. It also helps with stackability of the items.
While some of these reasons are true, the main reason is that stacking the cups takes up less space during transport and storage, saving money for the manufacturer, distributor, and retailer.
The main reason to make larger at top is so that you can stack glasses to store them more efficiently in the cupboard.
The widening lip helps to prevent spillage/leakage from under/around your mouth, while also giving the container significantly more volume. The mouth of a standard pint glass is somewhere around a foot long. They also allow the containers to be compactly stored by stacking/tesselating them. These three advantages far outweigh any advantage other shapes have.
Slippery cup + wet hand = dropped beverage.
So, cups have this design so that as gravity pulls the drink downward, the flaring taper counteracts that effect keeping it safely in place inside your hand.
If the taper went the other direction, as you squeezed your hand tighter, you could actually force the cup through your closing fist (kind of like squeezing a slippery bar of soap and it popping out of your hand.
Also, it’s WAY easier to store 100 cups if they all fit inside each other, than if they have to be individually placed on the counter. Uniform width, and fat bottomed cups can’t stack inside each other.
Edit: Typo
Cups are made that way so they are easy to release from the molds when they are manufactured. Also, it makes the cups stackable.
It’s easier to stack a cup that’s wider at the top than one that’s the same width the whole way up or one that’s wider at the bottom. It also makes it a little easier to drink, but I don’t think that’s as much of a reason as the stacking since just making it wide enough to drink easily the whole way down would also work.
I don’t actually know but I assume it to make the liquid easier to pour down your mouth without needing to turn your cup upside down to get something and potentially having everything spill because of how sudden it would be.
Also having a wider base and a narrow opening is bad for the environment. [https://www.youtube.com/watch?v=Hyq1uXzV1VE](https://www.youtube.com/watch?v=Hyq1uXzV1VE)
Less material is needed, generally the bottom is thick and the brim is thin.
Fluid dynamics also has a role, narrowing the opening will accelerate the fluid. Wider opening offers a lower flow which you can control better with your lips for make an opening you feel comfortable with.
You don’t have to lift the cup high to get the last drops.
And last but not least: stacking and molding both like to have narrow bottom and wider opening… which is the biggest reason: all of the above has exceptions, straight glass works just as well and many glass types have wide at the middle and narrow at the top.. Bottom being thick has more to do with balance than structural integrity but the bottom will always be thicker just because that is the surface that hits the table all the time. Multiple things are in play but wider opening glasses are usually always stackable and they are WAY easier (and cheaper) to manufacture without losing too much material. Long narrow glasses tend to have the problem that the liquid comes out too fast and unpredictable where as wider rim does everything “slower”. Wide in the middle is sort of compromise between the two, the distance from bottom to top is short but the opening is narrower (with cognac/brandy glasses, you need to tilt it more than usual, which puts your nose inside the glass… so there are many, many reasons for the shape)
Making the cups narrower at the bottom and wider at the top gives them a slight “wedge” shape, which makes it easier to put them into cupholders.
Without the wedge shape, if you try to fit a cup into a cupholder that’s too small, you can’t. With the wedge shape, even if the cupholder can’t accommodate the whole cup, it can probably fit enough of it to keep it in place.
There’s also the fact that it’s more ergonomic. Your shortest finger, your pinky, is at the bottom of your hand. When you curl your hand, the area inside is roughly conical, hence the roughly conical cups.
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