Sister sizing

Have you ever bought a new bra, but despite it being your size, it just doesn’t fit quite right? With a heavy heart, you consider you may need to return this new-in, limited edition, must-have piece of lingerie.

But stop right there, as you in fact might just need to change your size option.


Bra sizing never seems to be as simple as clothes. You have to take into account the style, plus both your back and cup sizes. Many bras seem to fit just that little bit differently and, of course, there’s your own unique shape and also what fit you feel comfortable in.

But getting that perfect fit isn’t that complicated. It’s often just that you need a slightly smaller back and larger cup, or a slightly larger back and smaller cup. The cup and band sizes work hand in hand. The secret is sister sizing.

Sister sizing, as it’s called, is a group of sizes that are the same cup volume. So if you’re a 36C, you could also potentially wear a 38B or a 34D – if the band size goes up then the cup size cups down, and vice versa. So if you’ve been fitted and told that you’re a 34F, for example, but find that while the cup provides good coverage with no gaping, you find the overall fit a little tight on the back for your personal taste, you may prefer a 36E. This gives you a looser, more comfy fit, but with the same cup volume as the 34F.

Using sister sizing is also a great way to get the perfect fit for certain bra styles and brands that size slightly differently to your usual size. We’ve listed some examples below to help you.


Sister sizes are sizes that have the same cup capacity but a different underband size. For example, someone who wears a 34DD, could also wear a 32E and a 36D depending if they want a tighter or looser fitting bra.

Tori Shelton, Figleaves garment technologist

Our garment technologist Victoria Shelton explains, “Sister sizes are sizes that have the same cup capacity but a different underband size. For example, someone who wears a 34DD, could also wear a 32E and a 36D depending if they want a tighter or looser fitting bra.”

So does this mean that if your new favourite that you simply must order today isn’t available in your size, you can simply try a size within your sister sizing range?

According to Tori, “Using your sister size is a great tool if your usual size is sold out, or a certain style isn’t fitting quite right. But if neither are fitting well, it’s probably a style that doesn’t suit your shape.”

Laura Barrett

Having styled for celebrity magazine shoots and written for many lifestyle brands, Figleaves Content Editor Laura Barrett is on hand to offer fashion news, style inspiration, trend updates and collection reviews.