For example, if your band size is 34 but your bust size is 37, then your bra size is 34C (difference of 3, again, means it's a C cup).

You'll still need your band measurement to give you the number preceding the letter. If the difference is less than 1, then it's AA, 1 means A, 2 means B, 3 means C, 4 means D, 5 means DD, and so on. From the difference between the two sizes, you can work out your cup. Then comes the slightly tricky bit: To work out what your cup size is, you want to subtract your band size from your bust size. Gently take the tape measure and measure it in inches as well. Once you've done the band, then you want to measure the fullest part of your bust. It's incredibly common for people to assume that they have bigger backs than they actually do (or be scared of having a larger cup size for the fear that it will limit their options). But don't worry-you're not alone in that mistake. The first thing you'll learn? You've probably been wearing the wrong bra size for a long, long time. That way, you can be on top of things when you're too busy to visit a lingerie department every six months. So although we would always recommend getting fitted properly, it is a great idea to be able to scope out your own bra size from home.

Our bodies change quickly (weight can fluctuate and our figures shift all the time), and wearing the wrong-size bra can be rather damaging to your breast tissue. There are loads of ways you get your bra fitted (and I do venture afield, as you'll see below), but the truth is that it's super-important to keep checking. Without the help of our bra-size calculator below, finding out (and updating) your bra size can be a time-consuming and downright annoying thing.

Finding the right bra size calculator