How to find a bra that fits you perfectly: Everything you need to know

How to find a bra that fits you perfectly: Everything you need to know

Bras must be right up there with jeans on the list of items that are notoriously hard to shop for and never seem to fit just right.

In fact, if I had to choose, I’d pick shopping for jeans over shopping for bras every time. I have pretty big boobs for my frame and like many women I grew up thinking of them as a flaw that did nothing but make it impossible to find bras, blazers and bikinis that fit properly.

Bras were never comfortable but I had always just accepted that bit of daily discomfort as the eternal fate of the big-boobed, and wearing bras in general as a necessary evil.

Fortunately, my whole bra experience changed for the better in the recent year when I discovered a small but vocal online community that's trying to fight the various misconceptions that exist around bras and help women finally find a bra that fits.

Bras aren’t uncomfortable by default. Not unless you are wearing the wrong size!

This post is a summary of everything I’ve learned from them plus a few other resources about finding well-fitting bras. I went from a European 80C to a 65F (36C to 30F in US sizes). That’s three band sizes down and three cup sizes up and let me tell you, the difference is amazing. Mind blown. 

Here's what we will cover in this post:

  • The cup size misconception: Why you probably need a bigger cup size
  • The band size inflation: Why you probably need a smaller band size
  • Sister sizes and why they are so important
  • Shape matters too!
  • 4 Steps to a better bra
  • What does a well-fitting bra look like?
  • Where to find non-standard bra sizes

Let's go!


4 Key Lessons


The cup size misconception: Why you probably need a bigger cup size

A major reason why so many women wear the wrong bra size (up to 80% according to various studies) is that they never get professionally measured but instead base their choice of bra size on common assumptions of what a B-cup or a D-cup supposedly looks like:

  • A = small
  • B = average
  • C = larger than average but not quite ‘big' yet
  • D = big
  • Anything above D = enormous

Ring a bell? The trouble is, those assumptions are bogus. Your cup size alone doesn’t say anything about the size of your boobs. It’s merely an indicator of the difference between your band size (the circumference of your back just below your breasts) and the circumference of your breasts. If there is a one inch difference you need an A-cup, if there’s a two inch difference you need a B-cup, a three inch difference is a C-cup and so on.  

Only together with your band size does your cup size reflect the actual volume of your boobs. The bigger the band size, the larger the volume: a C-cup bra with a size 30 band has less volume than a C-cup bra with a size 34 band. It’s all relative. That’s why you might well be an E-cup, even if you don’t consider your boobs to be particularly large, if you have a small frame and therefore need a small band size. If all of this sounds confusing, check out this helpful graphic from A Bra that Fits for a visual explanation of the relationship between band and cup size.

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).

4 Steps to a better bra

1. Get measured or measure yourself

Try this 5-point calculator or go get measured professionally (at a store that sells bras in the non-standard range).

2. Read reviews

Before you try on some bras in your new size, see what bra styles are commonly recommended for your breast shape and what others say about them. Reviews can also help you decide which size to try on since it's likely that you won't be the exact same size in every bra style. Good sources for these types of reviews and recommendations are A Bra that Fits, Bratabase and personal blogs with a focus on bras.

3. Try on lots of different versions

Once you have a shortlist of bras to try on, order a bunch of sizes online or try them on at a department store that stocks different brands. Use the criteria below to assess the fit of each bra you try on, and don't worry if you don't hit the jackpot straightaway. I probably tried on upwards of 20 bras until I found the first style and size combination that fit perfectly. After that it gets easier because you already know what type of bras work best for your boobs.

4. Beware of international sizing

As if bra sizing wasn't already confusing enough! Converting band sizes from US or UK to EU or AU sizing is relatively straightforward (just check this table right here). It's the cup sizes that you really need to watch out for, because all international sizing systems use letters to denote cup size, but above a D cup those letters don't mean the same anymore. I once ordered a bra from a UK site in my usual 30F size and it took me ages to figure out why the cup was way too big. Turns out I am only an F-cup in European sizing, but an E in UK sizes (and a DDD or F in US sizes). Bottom line: make sure you double-check what sizing system each bra is, and keep a conversion table on hand while you shop.


What does a well-fitting bra look like?

Here are some basic criteria to look out for:

  • The bra feels comfortable. This is hands-down the most important criteria.
  • It lies flat against your back without riding up or sitting too low. It's ok if the band digs into your skin a little bit since it should be tight, but it should never feel restricting or even painful.
  • The gore (the part between the cups in front) should lie against your chest (as opposed to float between them).
  • The underwiring should sit in your inframmary fold, not on top of breast tissue. The underwiring should also not dig into your skin below your armpits. Also watch out for breast tissue spilling out on the sides (that's usually a sign for a too-small cup or a shape mismatch).
  • The cups should lie flat against your breasts without gapping at the top or causing spill-over.
  • The straps should be tight enough to stay on your shoulders but without digging into the skin.

For more details, check out these two great articles:

Where to find non-standard bra sizes

Unfortunately, many lingerie brands still don't offer bras outside the standard 32-38 A-DD range. Here are some that do and where to find them online:


Online stores

Amazon and Ebay are also options.