Bra sizing can be incredibly confusing, so we're going to walk you through what the numbers and letters mean and how to figure out corresponding sizes. Once you understand how bra sizing works, it will make finding a bra that fits so much easier. This topic is so important and is going to change your world. Let’s get started!

Number = Band Size

The number in the bra size is your band size. Finding your band size is really easy. All you have to do is take a soft measuring tape and measure the base of your breasts or underbust. You want the measuring tape to be snug and not loose when measuring. Once you have your measurement, round it up to the nearest WHOLE number and that’s your band size. There is a chart below that shows you the corresponding underbust measurements with the band size.

Bra Band Facts

Here are some important facts about your band. Your band is where 90% of your breast support comes from, so it’s very important that your band is fitting correctly. It should fit snug on the loosest set of hooks when you first try it on. You want the band to be snug on the loosest set of hooks so you can tighten the band as it stretches out. That way the bra will fit you longer.

When you buy a correct fitting bra, it’s going to feel quite snug at first. Don’t worry, it won’t be like that forever. It will take a couple of days of wear for the band to ease a bit.  

When trying on bras, if you have to hook the back to the tightest set of hooks for it to be snug, you need to go down a band size or try on a different bra. Some bras have stretchier material in the band then others.  

There are two tests you can do to see if your band is fitting correctly.

The first is to put the bra on and move your arms around and jump up and down. When you’re done and if your bra hasn’t moved or if you don’t have to adjust the girls or pull it down, it’s snug enough.

The second test requires you have a partner on hand. Have your child, husband, friend, or a bra fitter try to slide their hand between the band and your back. If they struggle to do this, then your band is snug enough.

Every woman is different, but there are a couple of reasons we prefer bands to be really snug.

First, we like bras to last longer. If you're going to spend hard-earned money on a bra, it should last as possible.

Second, it provides extra support.

Third, the bra doesn’t move when you move. Who wants to adjust their bra throughout the day? You don’t have the time or the energy to worry if you're going to fall out of your bra. Your bras should be holding you in place. Sometimes we'll even go down a band size in certain bras to get more wear from the bra. 

If you try this, you have to go up a cup size to compensate the difference. (This will be explained more in the cup size portion of this post.) We don't recommend this to every woman. You may not find this comfortable or feel like you need to depending on your needs or what size you are. This works better for busty gals in need of more support or women who need a broader selection of bras.

"Back Fat"

A common complaint we hear from women who start wearing the correct fitting bra is back fat. Women don’t like the way the band is snug and it “squishes” excess skin on top and out of the sides of their back.

99% of women have some type of “back fat,” even very thin and athletic women. Men and women are not going to be looking at your back, people are going to be looking at your bosoms. You may be worried about looking "heavier" in the back, but if your breasts aren't supported, you'll look heavier in the front.

If you want to look slender and supported, the key is wearing the correct band size and making sure it’s snug. The band is the foundation of the bra and that is where you get support from. The bra band is like the foundation of a house. If the foundation isn’t strong (if your band isn’t snug), the foundation won’t be able to support the rest of the house (your boobs).  

Here are some examples of how wearing a correct fitting bra can make you look slimmer in the front.

Look at what a difference not wearing the right bra size looks like on the left compared to the correct fitting ones on the right. You can tell a huge difference! They both look like they lost at least 10 pounds on the right side pictures.

Wearing the correct band size is crucial for all women. Having a large bust can make you look heavier if you’re not wearing the correct bra size.

Letter = Cup Size

The second part to bra sizing is the cup. The number is the band size while the letter represents the cup size. This is the trickiest part of bra fitting and takes the most time to figure out, but if you follow these tips, you’ll be able to do it without any problems.

There are two ways you can figure out your cup size. We prefer one over the other, but we'll share both so you can get a better idea of what size you are.

The first way is to use our online bra size calculator. Here's the information you'll need to enter when using the calculator.

Start with a flexible tape measure and measure snugly underneath your breasts.

Next, measure the fullest part of the bust (bra on and shirt off).

Take a look in the mirror without your bra to evaluate the shape of your breasts.


Measure your waist and hips for your panty size.

After entering all this information, you'll get your size and bra recommendations!

For example, lets say your band size measurement is 36 inches and your bust measurement is 47 inches. Based on the calculator, you wear a 36H UK / 36K US.

The best way to find your cup size is going to a lingerie boutique that specializes in bra fitting. This is the most precise way to get a good fit. A good place should carry band or have access to sizes from a 28-52 and cup sizes from AA-J (UK).

I don’t recommend going to Victoria’s Secret to get fitted, go here to read why.

It’s worth it to invest in your bras because you're investing in yourself. Invest the time and energy to getting fitted correctly and purchase the correct fitting bra. You wear your bra EVERY DAY. Wearing the right one will make you look thinner, your clothes will fit better, and you will feel more comfortable.

Corresponding Sizes

The last thing we're going to go over in this post is very important. Everything on this post is important, but this will help you to manipulate the sizing chart and therefore, make you feel like a rockstar because you understand what happens to your size when you go up and down cup and band sizes. Also, by understanding this part, it can help you determine your size.

Another part to understand how sizing works is corresponding bra sizes. Did you know a 32DDD and a 36D are actually the same cup size? The only difference between these two sizes is their band size, the 36 is larger than the 32.

A 28DD has the same cup size as a 38AA.  So when someone says they’re a C cup, that doesn’t really mean anything without a the band size in front of it.

There are two things to remember when it comes to corresponding sizes. First, the larger the band size, the larger the cup sizes are while the smaller the band size, the smaller the cup sizes will be. You can be a large 38C or you could be a small 32C. The C cups in a 38 and 32 are not the same. A 38C cup size is three cup sizes larger than the 32C cup size.  For every band size you go up, the cup size goes up too.  

Second, whenever you go down a band size you have to go up one cup size to compensate the difference. If you go up a band size you have to go down a cup size to compensate the difference. 

Let’s pretend you wear a 34C but you've gained weight and your 34 band is too tight and uncomfortable. Your cup size hasn’t changed, so you'll want to go up a band size. Because you went up a band size you need to go down a cup size.  The corresponding size to the 34C is a 36B.

Bra Fitting

Now we’re ready to start putting our new bra knowledge to work. This is “Friend A”.

“Friend A” came into the shop wearing a 32B, shown on the left. After measuring “Friend A” for her band size she measured 26″ around. We put her in a 28 band size which is two band sizes smaller than the 32 band she was wearing, thus we had to go up two cup sizes.

“Friend A” ended up wearing a 28D.

You can tell she’s being covered correctly because the cup is flush with her breast, the center of the bra is lying completely flat against her skin, and the band is low and snug in the back. (She's wearing the Minx by Skarlett Blue.)

“Friend B” came into the shop wearing a 38E UK / 38DDD US.  She wanted to wear low-cut shirts while still feeling contained. After measuring under her bust, she measured 32″ around. That means she should be wearing a 34 band size.  Because we needed to go down two band sizes we had to up two cup sizes.

She tried on 34FF UK / 34H US and it fit her perfectly! See how much better she looks in a correct fitting bra. Her breasts are no longer sitting on her waist and she's getting lift plus the cleavage she was looking for. "Friend B" left wearing the Sabrina by Panache.

Bra sizing can be confusing and we hope this post helps you get a better understanding of how sizes are calculated.


Please let us know if you try out the Bra Fit Calculator! Just click on the button below to open it and get started. If you'd like to be measured by one of our expert fitters, please click below to book. We'd love to help!

If you've already ordered from us but wonder if your bra is still the right fit, book a Virtual Fit Check and we'll make sure your gals are in the best bra for you!