Your Best Fitting Bra: Sister Sizes Explained

Finding the right sized bra can feel like a minefield. Our bra size can change due to many reasons including the style of bra, brand, weight fluctuations and hormones. We all have an idea of our general cup size but it’s not unusual to find that, on occasion, our go-to size doesn’t quite fit right. Firstly, here are the signs of a well fitted bra:

• Straps should comfortably stay in place without digging into your shoulders
• There should be no ‘spillage’ over the top of the cup, regardless of style
• The centre of the bra (between the cups) should sit flat against your chest
• The band should be tight enough to offer the right amount of support without digging in or riding up. Being able to fit two fingers under the band is a good rule of thumb
• Cups should not gape or wrinkle
• Your bra should stay in place when you raise your arms

So, what if you try your usual size on and it doesn’t fit as well as it should? That’s where sister sizes come in. Every bra size has sister sizes. A sister size is essentially a related size where the band or cup size is different but the cup volume remains the same. Volume is the key here. Sister sizes allow you to tweak the fit of your bra without having to compromise on the all-important fit of the cups.

How Do Sister Sizes Work?

Each bra size has two corresponding sister sizes. To go a sister size down, you choose the next band size down and the cup size up. To go a sister size up, you choose the next band size up and the cup size down. Here are a few examples:

By being aware of your sister size, you instantly gain more sizing options which in turn gives you more flexibility when finding the perfect fit. Most of the support actually comes from the band rather than the straps or cups, so being able to go up or down by a whole band size could just be the key to finding your best fitting, most comfortable bra yet. Plus, it comes in handy if you can’t find your size in a bra you love – just reach for your sister size!