The band size inflation: Why you probably need a smaller band size

Cup sizes aren’t the only part of bra sizing that are commonly misunderstood, there are also misconceptions about band sizes, but they go in the opposite direction: women OVER-estimate the band size they need. Here’s why:

Most lingerie brands these days stock band sizes from 32 onwards. To the customer that suggests that 32 must be the smallest possible band size, that will fit only the smallest/thinnest women. The problem is that a 32 band size is actually closer to the middle rather than the lower end of the range, and it definitely doesn’t correspond to an XS in clothing sizes. If you are slim or have a narrow back you may need as low as a 28 or even a 26 band size to ensure your breasts are properly supported. Because that’s the trouble when you wear band sizes that are too big: Your bra can’t do its job.

Bras are designed to distribute the majority of the weight across your back. But to be able to do that, your bra needs to be tight enough so it can firmly hold onto your ribcage. If your band is just kind of floating on top of your skin, the entire weight of your breasts is hanging from your bra straps and put on your shoulders. And that is a surefire recipe for a whole lot of neck, shoulder and back pain.

So why do brands stock such a small range of band sizes if that means many of us will have to buy non-functioning bras?

Because of an old-fashioned bra measurement technique (called “Plus 4") and basic supply and demand. In the 1950s bras were made from non-stretchy materials like silk and satin and so customers were told to add 4 inches to the circumference of their backs to get their band measurement. Nowadays, most bras are made from stretchy material that already has great flexibility so it makes little sense to buy a bra that’s bigger than your back. And yet, again because not many people get professionally fitted, overtime people just kept buying the same size they were used to, meaning lingerie firms had no reason to spend money to expand their repertoire of sizes.

Sister sizes: The secret to finding a bra that actually fits

Ok, so we’ve covered why so many women wear the wrong bra size: misconceptions about what certain cup and band sizes look like.

If you suspect you may not be wearing the correct size either, there’s one more concept that you need to know about: sister sizes. Sister sizes are bra sizes (band + cup size) that have the same cup volume. For example: 34C and 32D are sister sizes. So are 28E and 30D, or 36B, 34C and 32D. Basically: As you go down a band size, you go up a cup size, and vice versa. Check out this chart for a complete list (all sizes in a row are sister sizes and will have the same cup volume).

Understanding how sister sizes work will make it easier to hone in on your correct size as you try on different bras. You might for example find that a 34B has just the right amount of volume in the cups but is a little too loose in the band. In that case you know you need the sister size with a smaller band, i.e. 32C. On the other hand, if you find the band is way too tight, you could go the other direction: up a band size, but down a cup size to get the same volume, and end up with 36A.

But again, because of the typical misconceptions people have about bra sizes, that second scenario is much less likely than the first scenario. Most women don’t need to go down a cup size, but up! And not up a band size, but down.

Shape matters too!

Unfortunately, finding a great bra takes more than knowing your true size. Breasts come in so many different natural shapes that couldn’t possibly all fit the same bra shape equally well.

On forums like A Bra that fits you will be able to find plenty of pointers for what type of bra works best for what type of breast shape, but these aren’t hard facts, just recommendations because plain personal preference also plays into it. So be prepared to try on as many different bras as possible until you find your favourite(s).