Band Size and Cup Size Are Not Dating
They Don’t Come as a Pair
What does it mean that band size and cup size are independent?
FIT GUIDE
brabar
FIT GUIDE
BRABAR
FIT GUIDE
Bras are a complex issue, so it is incorrect to group your cup and band size together as they are equal parts of the same things, so let BRABAR tell you abut the difference.
By: Lucy DiChristina
In this article, we're decoding one of the most misunderstood parts of bra sizing: how band sizes and cup sizes work together without being the same thing. Band size and cup size measure two different parts of your body. Neither works without the other, and together they determine your starting bra size. You'll learn why the number is just as important as the letter, why online calculators and retailers often give different answers, and how limited size ranges can leave girls thinking they're the problem when they're not. The biggest takeaway? Your bra size is about measurements, not labels—and your body was never the thing that needed fixing.
Do you guys remember learning about height, width, and volume in like third grade? Well the bra industry either missed this science class or has just decided to completely ignore facts of figuring out the size needed to hold something, and honestly I don't know what would be worse. When the American bra market is flawed at its core a lot of misconceptions have been able to spread about bra sizing, and how your cup and band work together to create the perfect fitting bra. One of the biggest misconceptions when it comes to finding your bra size is that your cup size is the most important part of a well fitting bra. While your cup size cannot be sacrificed it also only accounts for 20% of your bras support. Even though your band and cup size are not eternally interlinked, they also cannot be taken as completely separate measurements, they are independent but still work together to create the bra that matches your body's measurements.
What Does My Band Size Mean?
Here are the answers that everyone is looking for but no brand will outright tell you, let's break down exactly what your band and cup size are and what their significance is in building the perfect bra. Your band size is the measurement of your ribcage (underbust). Don't let the brands confuse you, it really is that simple. Generally women's band size ranges from 28-56 (this is the set of numbers in your bra size). So why do most bra brands sell a range of 32-42, only nearly half of the sizes that would fit into this range, and why is it that the brands that do sell a larger range of band sizing are considered “speciality” and "extended" bra sizing brands? Oh and if that is the case then wouldn't that be setting women up for failure and to spiral about being the problem when they can't find bras that fit? It absolutely would be and absolutely is, which is why so many women are wearing bras that show signs of them either being too tight or too loose.
What Does My Cup Size Mean?
Cup size is a little more complex. You find your cup size by subtracting your underbust (ribcage) measurement to your overbust (breast) measurement. The number that results from this simple subtraction then corresponds to a letter. Once again there is a disparity between cup sizes generally worn by women (AA-N) and cup sizes actually represented in the market (AA-DD). Once again I remind you there is no acceptable reason that the cup size range on the market is so limited that it forces women to have no choice but to wear the wrong size bra. There is a revolution needed to hit the bra market and we are here to start it.
"without your accurate band size your cup size means nothing"
How Do My Band Size And Cup Size Work Together?
Ok, so now that we know what each aspect of our measurement means, how do these two measurements come together to equal one perfectly fitting bra? Let's work backwards and let me point out arguably the most common bra misconception. We have discussed how cup size is simply the difference between your underbust and overbust. It would make sense that technically one cup size does not necessarily accommodate the same size bust. A 30D and a 36D are built to accommodate a completely different set of breasts and therefore have different shape and volume cups. So yes, this means that without your accurate band size your cup size means nothing, however certain band sizes and cup sizes should not be immediately grouped, and this is where the nightmare of sister sizing comes into play.
What Is Sister Sizing?
Sister sizing is the way that bra brands can pretend that they are accommodating every single breast measurement. Sister sizes have similar cup volume, but different band lengths and proportions. They can be useful in some situations, but they are not a substitute for finding your anatomical starting size. Sister sizing would support the belief that a 34D and a 30DDD, however we have learned that this is not the case. Not to give anyone trust issues, but this is also why when you put your underbust and bust measurements into bra size calculators on popular retailers websites you will be given completely different sizes, which all don't truly fit you. It is because they are squeezing you into the best bra for you that also happens to exist within their brands already existing sizing. In this way brands profit off of their thought that women don't actually know what to look for when finding the right bra size. So this is where the volume analogy comes in. We learn that cups with different measurements can still have the same volume, however if this is the case then all of the cups also happen to be different shapes. Although this is not a problem when it comes to scientific volume it is a problem when it comes to bras because the whole point of different size cups of a bra is that they accommodate different shaped breasts. When it comes to boobs you absolutely cannot disregard the shape the results from messing with measurement even if they equal the same volume.
Wait, So I'm Not The Problem?
The frustrating part is that many women never realize the problem is the sizing available to them. Instead, they assume the problem must be their body. When every bra in a store feels uncomfortable, it is easy to start believing that you are difficult to fit, that your proportions are unusual, or that bras are simply supposed to feel uncomfortable. Over time, these experiences can create a cycle of frustration where women stop expecting bras to fit well at all. Perhaps the most damaging consequence of limited sizing is the message it sends. When brands fail to offer sizes that reflect the full range of women's bodies, they indirectly tell customers that their bodies fall outside of what is considered normal. Instead of questioning the limitations of the products being sold, many women end up questioning themselves. The truth is that a bra not fitting your body does not automatically mean there is something wrong with your body. Sometimes it simply means that the industry has failed to create products that accurately reflect the diversity of women's measurements in the first place.
One Last Thing Before You Go
The next time someone tells you that you're "just a B cup" or "a D cup," remember that bra sizing doesn't work that way. Your band and cup size work together, but they are not attached to one another. They are two separate measurements that tell two different stories about your body. Understanding that difference isn't just about finding a better fitting bra—it's about realizing that your body was never the problem. The sizing system was.
XOXO BRABAR
STILL HAVE QUESTIONS?
FAQS
Yes. A cup letter by itself doesn't tell the whole story. For example, a 30D and a 38D are not the same size. Cup volume changes depending on the band size, which means the same cup letter can represent very different breast volumes and shapes. That's why your full bra size—not just the cup letter—matters.
Many retailers use sizing calculators designed around the sizes they currently sell rather than your exact measurements. If a brand doesn't carry your true size, their calculator may place you into the closest available option. This is why you can enter the same measurements on multiple websites and receive several different size recommendations.
Band size and cup size measure two different things. Your band size reflects the circumference of your ribcage, while your cup size reflects the difference between your bust and underbust measurements. Neither measurement is more important than the other, and both are needed to determine a bra that truly fits your body. A cup size without a band size is incomplete information.
