This Is Why Your Milk Jug Has a Circle On Its Side

Have you ever looked at a milk jug and wondered what the purpose of that circle on the side of the container is for?

The next time you go to the store, or even when you open up your fridge, check out your jug of milk. You'll notice a pretty good-sized circle on the side of the jug. Maybe you have noticed it several times in the past, or perhaps you haven't really thought to examine your gallon or half-gallon of milk before. Either way, that circle on the side of the jug isn't just there for the sake of design, it actually serves a couple of important purposes.

What's Up With The Circle On The Side Of Milk Jugs?

Most gallon and half-gallon jugs of milk will feature a circle intended on the side of the jug. These "dimples" serve two major purposes that perhaps you didn't know about. Let's take a look at them.

Expansion

These circular indentations allow the milk jug to flex slightly, rather than keeping a solid, rigid shape. According to Distractify:

Expired Milk

Another cool feature of this circular indention, and probably the most useful reason is to help let you know if the milk is expired or not. We all know that sometimes those expiration dates that are stamped onto the milk can be hard to see. Well, that's where the circle comes in.

Distractify explains that as your milk gets older, the bacteria (not all of which are bad) create gas inside of the jug, which causes it to expand. So, if the circular indention has started to expand, that would be a good time to check the expiration date. If you can't see the expiration date, and that circle has popped out a lot, it's safe to just discard the milk and get a new gallon.

So there you have it! The case of the circle on the side of your milk jug explained. If you didn't already know, now you do!