Bra fitting

Online Bra Size Calculators Are Misleading, Terribly Misleading

I’ve mentioned multiple times so far that my ‘true’ bra size is 30F. But really, how did I come up with this result? I used an online calculator and then tried on bras in store, having a good idea of how bras are supposed to fit. However, when I went in store and told the fitter I measured myself as 30F or 30FF, she told me we’d need to try on some bras to confirm that, and there’s a good reason to this: online bra size calculators are VERY frequently misleading, even extremely misleading.

Let’s take the time to measure exactly how misleading these calculators can be.

My measurements are 30″ loose underbust, 29″ snug underbust, 28″ tight underbust, 36″ standing bust, 38″ leaning bust, 36″ standing bust. Why did I take that many measurements? Because the most precise calculators can use all those 6 measurements, although most of them use only 2 measurements: snug underbust and standing bust. However, some weirder places, like Victoria’s Secret, also use another measurement instead of the underbust, which I took just for fun: the perimeter passing at the height of the band in the back and over the bust, which comes up at 35″ for me.

First, let’s calculate using the basic math I talked about in this post. My snug underbust is 29″, which puts my band size at 30, and my standing bust is 36″, 36 – 29 = 7″, which comes out as an F cup in UK sizing, or a G cup in US sizing. The other 5 measurements become useful if, for example, there was a big difference between my snug and tight underbust measurements, which could mean I’d want to get a number between the two instead of rounding up the snug measurements. It could also be useful to consider if my leaning bust was 3″ or more bigger than my standing or if my lying measurement was bigger than my standing, which could mean I’d need a FF or a G instead of F. But, since it’s not the case, 30F usually does the trick for me, so let’s go with that as my reference mark!

So, let’s start with stores that are familiar to me! La Vie en Rose is a Canadian lingerie company dedicated to the well-being of women. Their price tag is mid-range, they usually come up between CA$40 and CA$50, which is more expensive than La Senza and Victoria’s Secret. They carry sizes 32 A-C, 34-38 A-DD and 40 D-DD. Yeah, that’s right, they don’t go above C in 32 or under D in 40 (they may have 32-36 AA and 32D in some styles). They don’t have a size calculator, but here’s how their size chart works:


So… According to this chart, I should wear a 34C. Fairly normal, right? But 2 whole band sizes off and 2 cup sizes off too (my sister size in 34 is DD). While their grading would put people with 39″ underbusts in 38, which may actually be the right size, and people with 40-42″ underbusts in 40, their band size chart doesn’t get accurate until you are at least 32″ under the bust. Under that, they will fit you in bands that are too big for you. The cup size chart doesn’t make much sense either, with the increase between cup sizes being 3/4 of an inch instead of a full inch, which doesn’t make much sense. But it gets a bit weirder:


That’s right! La Vie en Rose knows about sister sizes! But they are totally oblivious to the fact that a bra should always be tried on on the loosest hook, not the middle one, and the fact that the small space between the hooks will not make a band that is 2″ too big to begin with a better fit, or a band that is 2″ too small less constricting (but that’s only if you were wearing the right band size to begin with). It can help someone stuck between band sizes or on a model that runs particularly tight or loose. But it’s not something to do “when your size is not available in the desired style”, as they put it, because wearing a band smaller than you need can quickly become uncomfortable, while wearing a band bigger than you need on the tightest hooks means the bra will stretch out too much to be wearable within less than a few months.

Now on to La Senza:


La Senza are so nice that they even did the math for me! I’m a 34C according to their handy size chart, again 2 band sizes too big and 2 cup sizes too small! If I was a normal person, I’d be very inclined to think that, since the two major bra stores in Canada tell me the same size, then they must be right. That’s to tell you how common my measurements are (enough that they take them for example), and how many women may be wearing the wrong bra size. However, as opposed to La Vie en Rose, La Senza consistently fits people in bands that are 2 sizes too big.

The last but not the least of mainstream stores is, of course, Victoria’s Secret:


Yeah, they’re the one using the weird measurement I took earlier on. They tell me I’m a 34B, so still 2 band sizes off, but this time 3 cup sizes too small. The weird thing is La Senza and Victoria’s Secret are owned by the same company, L Brands, which also owns Bath & Body Works, so I’d figured out they’d be using similar bra sizing techniques, but apparently not. La Senza was originally created in Canada but has always used similar marketing techniques to VS, so it was only natural that they’d be owned by the same head company at some point.

After these 3 companies, which are total disasters, I figured I would give a try to more specialized lingerie online stores and went with the 2 most popular online stores in North America: Herroom and Bare Necessities.

I’ll start with Herroom, since they make a big deal out of helping women finding their proper bra size:


I strongly suspect many people would feel overwhelmed by the amount of links they can clic and read through. It effectively seems like this website contains “Everything You’ll Ever Need to Know” about bra fitting. But the bra size calculator, what’s it worth?


Yup, they’re a band size off and 2 cup sizes too small. I have some old Passionata bras in 32D… And they’re awful: gore floating, band riding up with no support, straps digging in, quad-boob syndrome, etc. I’ve already dared to contact them about this matter and was met with a rather cold response indicating that it works fine for other women and they can’t make it perfect for everyone. Here’s their manual instructions:


It’s funny, but their advice concerning band sizes is only accurate after 38. They also inaccurately give the same cup size to people with different underbust measurements: someone with a 35″ underbust will be, according to their calculator, the same cup size as someone with a 38″ underbust if both are, let’s say, 40″ in the bust. In reality, those 2 people would need 2 very different sizes, the person with a 35″ underbust needing a 34DD/E or a 36D/DD, while the one with a 38″ underbust would need a 36C or a 38B (depending on their tight underbust measurement), as they’ll have very different breast volumes.

The fact that they mention that their calculator/calculation method is inaccurate after 4″ of difference between the bust and the band size and if people have pendulous breasts is quite curious for a website that stocks 974 different “Full Figure DD+” models and 590 “Plus-size” models, meaning that a good portion of the people shopping on their website fall out of their calculator’s accuracy range, which makes their size calculator quite nonsensical. It’s also quite curious considering that pendulousness doesn’t really influence the measurements (apart from the leaning bust measurement) and sizes as much as the shapes of bras, which they claim to have good knowledge about. I’m not going to take the time to break down the advice they give concerning bra styles as they give a lot of flawed advice, but I’ll let it be known that their categories are pretty much made-up. There is no such a thing as “petite” bras, they are conflating cropped bustiers with longline bras, they’re describing sports bras as “bras without underwires” (?), and they’re lumping together any and all 3-part cup bras, while 3-part cups are just a design feature and not a specific cup shape.

Now, let’s move on to Bare Necessities.


Yeah well, Bare Necessities doesn’t want you to measure. They consider that if you have fitting issues with your current bras, analyzing those issues should suffice to readjust your size. But the problem, as I have highlighted above, is that people who are feeling frustrated with their bra sizes are often multiple sizes apart from their true size; just being told to go down a cup/up a cup or down a band/up a band may not do much more than directing women to bras that they believe are the ideal fit, but are not, because they have no idea how a bra is truly supposed to fit. This approach also negates the many ways in which cup shapes can influence fit, or how wearing the wrong cup size can actually make you believe the band is tight enough/too small. Their “Check your Fit” page or “troubleshooting guide” don’t actually give much accurate advice about how to take care of these problems, and they are pretty oblivious about how shapes may influence fit. They still do give some calculation method to get a “starting point”, which is really what calculators are about anyway.


So, first thing: do NOT measure over your bust for the band size. It’s a handy way to overestimate band size that’s been used by many mainstream companies. It’s especially worse for people who have tall breast roots and/or V-shaped ribcages and/or muscular torsos. Everyone should measure for the band size where the band is supposed to pass (doing anything else is pretty illogical as, well, you’d want to know how large is the spot where the band is passing, not how large other spots are). As for the cup size, Bare Necessities also makes the mistake of advising to calculate cup size from the band size instead of the ribcage measurement, which doesn’t make sense but would still leave me one shy cup size away from my true size, with the right band size, which would be a 30E.

So, if all of these calculators are inaccurate, do I have a better option for you? Somewhat.

The most accurate calculator that I know of is maintained by the A Bra That Fits community of Reddit. Their calculator is not 100% perfect, but it gives a much closer idea of band and cup size that can actually be used as a base to figure out your best fitting size.


The pros of this calculator compared to others are numerous:

  • Taking into account 5 measurements and having a more complex calculation algorithm means being able to suggest bra sizes fairly accurately for people down to 24 band size, up to 46 band size (but bras exist up to 52 and beyond) and up to MM cup size (but a few sizes exist beyond that too).
  • Calculating things like the leaning bust gives a potential hint about breasts being pendulous or having softer tissue (which can bring their own fitting issues).
  • Calculating breast size when naked means your breasts can’t be distorted by a too small or too big bra, which makes for more natural and accurate measurements.
  • It suggests sister sizes, which are sizes in a different band but same cup volume, and puts up a warning when it’s likely that one may want to sister-size up for comfort or down for support.

But even if this calculator is more accurate, as a general rule, than others, it still suggests UK 30G for me, while my true size is UK 30F, because it can overestimate cup size in pendulous breasts that have a tinier difference between the leaning and standing/lying measurements. So even when you get the best calculation method out there, the results are still nothing more than a starting point, as bra fitting is not a science but an art. For what it’s worth, I would definitely recommend this calculator over the others shown in this post. Some indie bra shops also have fairly accurate size calculators, but from experience I can say that you should not follow what a size calculator tells you just because it’s a brand’s size calculator (be especially wary of calculators that put you in bigger band sizes than the usual). On contrary to what they may tell you, bra sizing is rather standardized, and they should not, and will not as a general rule run 2 band sizes smaller than other brands. Use what you know of your true size or contact the brand owner before ordering if need be, but not all bra designers actually know much about bra sizing, so don’t just trust people with your measurements!

Anyways, this is just to show you how the discourse about bra sizes can be confusing, even in places that claim to be specialists about bra sizing. So be careful, don’t buy things because someone tells you to buy them and trust your gut feeling when it comes to bras. Every little annoying thing about a bra you are trying on will get worse as you wear it (except in most cases fabric texture and band tightness).

Stay supported,


Note: This post is not meant to bash mentioned (or not mentioned) brands or stores, bra fitters, or anything or anyone else. It is also not endorsed by or supported in any way by any of the cited brands/stores. I do not mean that you should boycott those stores or brands, or that you are necessarily wearing the “wrong” size if you wear bra sizes that you found using these places’ calculators or following advice from bra fitters in these places. There are no right or wrong sizes, only best fitting sizes and less-than-best fitting sizes. This is simply meant as an illustration of how bra sizes are actually not well understood even within the industry, so it is normal that it can get very frustrating for people to try and find their best fitting size.


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