The size of our boobs can change for a number of reasons, including if we lose or gain any weight, but lots of us are guilty of getting measured and sticking to that size for years. So how do you know if you're wearing the right bra? And how often should you buy a new one?
Marks and Spencer's bra fit expert and technical manager Julia Mercer has spoken to the Mirror Online to answer these important questions.
How do I know if I'm wearing the right bra?
There are a few tell-tale signs that you're not wearing the right size bra.
This is when it looks like your boob is coming out under the cup. It's caused when the underband is too big and the cup is too small.
This is when the boobs spill out of the side. It's caused by the cup being too small. It can be very painful.
To check the cup fits correctly, make sure it is fully encasing ALL the breast tissue.
You should adjust your straps so you can just fit two fingers on top of each other underneath.
A good way to check if your bra is giving you enough support is to slide the straps off and see if the cups are still supportive.
The straps are designed to hold the cups up, not to give support.
The four-boob effect
This is when the incorrect cup size pushes the tissue up. It can look very unflattering when you're wearing clothes.
According to Julia: "Unfortunately every woman, no matter their size, has this issue and can be made worse if the underband of the bra is too tight.