What Are Bra Sister Sizes?

Sometimes you just need a particular bra. Sometimes you just fall in love with a little cute bra and no other bra or bralette seems to work for you. It may be the case that you lose it for lingerie, like us. Or, maybe, the dress or top you wear can only be worn with that special bra and no other style will make you look stunning.

The wrong bra can ruin an outfit, right? What happens when that perfect bra isn’t available in your size? Don’t panic. We’ll show you a trick that will save the day: bra sister sizes. Keep reading and find out why sister sizes are the best thing since sliced bread.

Good fitting dd+ bra by Chantelle

Bra Sister Sizes: An introduction

Before we tell you how to find out what’s your bra sister size and because you may not be an expert on lingerie, let us quickly explain how bra sizes work:

  • Back sizes: also known as underbust sizes. Take a measuring tape and measure around your body, right below your bust. Did you measure it in inches? Round up and you’ll get your back size. This is: 30, 32, 34, 36, 38, etc. Did you measure it in centimetres? Then round up to the nearest multiple of five and you’ll get your back size in the European scale (eg. 80, 85, 90, 95, 100, etc.).
  • Cup sizes refer to the volume of your bust. It starts from A cup, then B, C, D, etc. You have a detailed explanation of how to find out what’s your cup size here. You should know that cup sizes vary from one country to another. This difference becomes more noticeable with the ample bosoms. In the United Kingdom, for instance, we have a DD cup size in between the D and the E cup, while other countries also include a DDD, in between the DD and the E cup.

Bra sizes are different all around the world

Yes, you must have realised now that bra sizes are different all around the world. We know this can feel confusing, but hopefully, our International Bra Size Conversion chart will make it easier for you.

Bra sister sizing explained

As you know, sometimes it’s difficult to find the right bra for you. We’ve all been there. A bra in a size 34 D may be too loose, but, then, the 32 D is perfect in the back… until you realise there isn’t enough room in the cup. This is why sister sizes aren’t always a bad thing. We’ll talk about that later.

Now, take a look at the table below with all the sister sizes for the bra sizes we currently stock. Loads of sizes, right?

graphic with sister sizes equivalences
Bra sister sizes in the United Kingdom. Source: UK Lingerie
  1. Find your bra size in the table above.
  2. Look at the very left and very right of your size. Those are your sister bra sizes.

Example: If your usual size is UK 34 C cup, your sister sizes are UK 32 D Cup (on the left) and UK 36 B Cup (on the right).

Bra sister sizes don’t always work

Bra sister sizing has a little bit of a bad press. For instance, if you are buying a bra in a small boutique and they don’t stock the bra you like in your particular size, they may use this technique to find a bra that fits.

You can use this tip when you fall in love with a bra that’s not available in your size… but happens to be available in your bra sister-size up or down. Although useful, this technique doesn’t work 100% of the times and it cannot be a substitute for a proper bra fitting. However, it’s an amazing bra fitting solution to find that perfect-fitting bra.

In with situations are bra sister sizes handy?

If the back of your bra is a little loose, but the cup volume is perfect, sister-size down! Using the previous example, if a UK 34 C cup feels is riding up because it’s too loose, try on the UK 32 D Cup.

Do you have any questions about bra sister sizes or any other lingerie fitting issues? Get in touch and we’ll do our best to help!

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