Tuesday, March 13, 2012

Underbust Survey - Part 5: Clothing Sizes

Part 1, Part 2, Part 3, Part 4, Part 5

I've always wondered how clothing sizes were determined because human bodies (especially female bodies!) vary so much that it has to be nearly impossible to pick Bust/Underbust/Waist measurements to base shirts off of.  That's not even thinking about adding in High Hip and Hip measurements into the equation (so we're not going to be discussing dresses here).

In this part I wanted to answer the following questions:

  • How closely related are Waist and Underbust measurements?
  • Using Waist size as a base, are there any clear winners for Waist and Underbust measurement that clothing sizes could be based on?
  • How do my results compare to an average size chart?
In all of the following I only used responses that included a Waist, Standing Bust, and Underbust measurement.  In total I had 178 usable responses. 

So now on to tackling these questions:

Relationship between Waist and Underbust

In my blog I've often assumed that Waist=Underbust within a variation of about 1-2 inches either way.  I wanted to test this assumption (my gut feeling was that for smaller women Waist<Underbust and for larger women Underbust<Waist but that was something else that I wanted to test).

First, taking out the weight factor, I found that as suspected using Waist=Underbust isn't a horrible assumption
However, it does appear that Underbust tends to be larger than one's waist.  Granted, as I discussed in Part 1, I have just over 50% of respondents who are within the healthy BMI range so we are looking at a somewhat higher than average number of "healthy" respondents than what you'd see in the US, for instance. 

If we break down the variance by BMI we then find
As you can see the variance between Underbust and Waist is all over the place!  As I thought in the very high end of BMI it looks like it's more common to have a larger Waist than Underbust but even at the lower end it's all over the place.  I think it rules out the idea that every woman at a healthy BMI has a flat stomach too.  Interesting!  However, it does look like women with BMI's under 20 have Underbust>=Waist.

Size predictions

In this section I separated all the responses by their waist measurement and then looked at the average occurrence of their corresponding bust and underbust measurements.  I used waist measurements between 24"-33" because I had at least 10+ responses for each waist size (with the exception of 32" where I had only 8 respondents with a 32" waist).  For waist measurements 34" and above I always had 5 or less respondents so I didn't include the results because the statistics were not very good.  Granted, that is typically considered the plus-sized region and plus-size clothes tend to cover more like a 2 inch waist range or more for each clothing size so I may go back again and try to redo the results for a wider waist range in the 34"+ region. 

Without further ado here are the results:

In terms of the number of respondents for each waist size I had:
  • 17 with 24" waists or under
  • 14 with 25" waists
  • 21 with 26" waists
  • 10 with 27" waists
  • 22 with 28" waists
  • 23 with 29" waists
  • 14 with 30" waists
  • 13 with 31" waists
  • 8 with 32" waists
  • 10 with 33" waists
  • 26 with 34" waists or above (although always 5 or under for each respective waist)
So what exactly do all these results mean?  Well, one thing is obvious, depending on the waist size we see there there is quite a bit of variation still for the underbust and bust size. I really wish I had had more responses in each specific waist size range because it's hard to draw any definite conclusions from this.

Comparing to Size Charts

I had the most respondents who had a 29" waist so I wanted to compare that graph specifically with various size charts.  For women with 29" waists, 43.5% had an underbust in the 29-30" range and 91.3% had an underbust in the 27-33" range, that's quite a wide distribution!  In terms of bust size 47.8% has a bust size in the 38-39" range, 70% had a bust size in the 36-39" range and 91.3% had a bust size in the 36-42" range.  Point is, it's very hard to peg down corresponding measurements just based on the waist size alone.  If you wanted to get in about 90% of women with a 29" waist you'd need to have a top that fit a bust over a 6" range and an underbust over a 6" range also!  Basically, you'd have a tent.

Now, there are some work arounds here.  For instance, empire waist tops only have two measurements that are relevant (underbust and bust measurement) whereas flowing peasant tops really only rely on bust measurements when it comes to finding a good fit because they are not meant to be fitted around the waist/underbust.

I think looking at these measurements it becomes quite clear why manufacturers turn so often to Spandex because you're going to reach a larger percentage of women.

Now the question remains... what about stores like BiuBiu, Aj Rumina, Carissa Rose, Campbell and Kate, and Pepperberry who go by both a waist and bust size?  Can they get a better fit?

In the case of women with a 29" waist, just using the percentages it seems like it would make sense to divide the bust sizes in the following three categories:

  • 34-36" covers 21.7%
  • 37-39" covers 56.5%
  • 40-42" covers 21.8%
So let's see how that lines up to some of the brands listed above.  For BiuBiu a 29" waist corresponds to a size 38.  And the size cover
  • 38B 35.8-37.4
  • 38BB 37.8-39.4
  • 38BBB 39.8-41.3
Ok, wow, those numbers match up extraordinarily well!  I'm curious, though, if BiuBiu sees a higher percentage of their 38BB shirts sold compared to their 38B and 38BBB? It would be interesting for comparison.  Now, the bust measurements from my survey do fall slightly below what BiuBiu sells but then again, BiuBiu caters to large breasted women and I specifically asked women of all sizes to respond. 

Let's check the same with Pepperberry.  According to Pepperberry's size chart a 29" waist corresponds to a size 10 and the curve sizes are as follows:
  • 10C 33.9-35.4
  • 10RC 35.8-37.4
  • 10SC 37.8-39.4
so it looks like the measurements from Pepperberry run exactly a size smaller than BiuBiu and miss out on roughly 20% of the population on the larger bust end.  Granted, I'm sure some of the top 20% can still fit into their range if the material is stretchy and depending on the cut but it does appear that the Super Duper Curvy could be needed.

However, at least according to my survey, it would be useful for manfacturers to list the corresponding underbust measurement.  I found quite a wide range in underbusts for women with a 29" waist and that will make a large difference in the bust size.  If you have a women with a 29" waist, 27" underbust and 40" bust (let's call her woman A) she is going to have very different fit needs when it comes to tops as compared to a women with a 33" underbust and a 40" bust (let's call her woman B).  Actually, if they were looking at tops like the BiuBiu Fuego
Woman A might very well prefer to size down to a 36BBB whereas women B might want to size up to a 42B.  Granted, woman B might also need to take in the waist on the 42B but it might give her the best fit in terms of the underbust/bust combination.

So what's the solution here?  Well, my personal preference would be for manufacturers to simply list the measurements that a shirt is made to fit.  For instance, on the Fuego top listing the Underbust and the Bust measurement are much more useful than listing the Waist and Bust measurements (by the way, this is not me trying to pick on BiuBiu here- it just happens to be one of the companies that I've drooled over the most so I'm also more familiar with the clothes they offer). 

Now, clothes that are fitted throughout the waist and underbust are certainly trickier.  For instance, the Deadly Dames Courtesan Wiggle Dress found in Pinup Girl Clothing

It's a gorgeous dress but it certainly must provide a lot of challenges when it comes to fit. 

Let's take the 3 size divisions that I chose above and call them 29small, 29medium and 29large.  If we compare this to the underbust reported we really don't see any clear division
I chose not to convert this into percentages because I wanted to demonstrate that we do have a relatively small sample size here.  Despite that, the point is that a dress that is fitted around both the underbust and waist is going to be a difficult fit for many women because there is such a high level of variation in his region.  I wonder if it wouldn't be easier to fit the bust and underbust, while leaving the waist somewhat larger and then offer in store alterations for a small fee?  This could easily be done on a website too if the woman provided her waist measurement.

I'd love to hear some feedback from clothing manufacturers, how do you deal with these issues?


  1. So much to digest from what you've written. I literally was googling "What is larger, a woman's waist or her underbust?" before you tweeted the link to this post just now. That's because I'm about to publish a post on the Campbell & Kate blog showing how a 10S, 10M and 10L fit a woman with a larger waist than underbust.

    When I took the Eveden bra fitting class, Freddy (the instructor) told us that a woman's underbust is smaller than her waist. That's the principle that Carissa Rose operates under as well.

    On the other hand, I've always operated under the assumption that the waist is smaller than the underbust. Your survey results show that it can go either way, which is super helpful and interesting!

    My current hypothesis is that it is best for a full-busted woman to choose a size based on her largest and smallest measurements. She should then choose the waist measurement in the company's sizing chart that matches her smallest measurement.

    So Woman A in your example would choose a top for a 27" waist and 40" bust. Woman B would choose a top for a 29" waist and a 40" bust. Although Woman A's "waist" will be higher than the waist on the shirt, there should be enough ease at the waistline to accommodate the fact that she is slightly larger there. (I think that may be what you did in your example where you had Woman A sizing down, but I haven't studied the BiuBiu size chart to make sure.)

    And dresses are another story entirely! It's not just the bust and underbust, but now you've got hips in the mix!

    I think you're right, though--if there can be a way to take in the 2nd largest part part of the body AFTER THE BUST, while fitting for the smallest part, there might be some happy full-busted customers out there, regardless of the size of their underbust, waist or hips.

    1. That's crazy that you were actually googling this while I wrote it. :D I'm glad it's very relevant then!

      It's something that I've always wondered about because I so often see clothes that are clearly designed for women with larger underbusts than waists (and being that I have a smaller underbust than my waist, I've often found myself frustrated with the cut on certain clothes). I do think that often women who are natural hourglass shapes (the Disney Princesses from my previous posts) tend to have larger underbusts than natural waists. But it seems like amongst the population as a whole it's all over the place.

      That's an interesting theory about fit. I suppose it depends on the stretch in clothes. As someone with a smaller underbust than natural waist, I'd say it works about 50% of the time. ;) Clothes that are looser around the waist, have more stretch, or are fitted around the underbust allow for me to size down. Clothes that have the focal point at the natural waist, well, don't tend to be as flattering on me and I also have to size up for them.

      Yikes, and I have to say, I'm happy that I don't design dresses for a living because there are way too many parameters to fit!

      But like you said, I do think something we can take away from this is the more information that we have as consumers, the better. I'd love to see underbust, waist and bust listed separately on clothes because I a 2" difference between the two, which could be a difference in 1-2 clothing sizes depending on the cut and material used. Makes online ordering quite difficult! I've found the same when it comes to pants (once I understand what the corresponding high hip measurements translated into for each pant size) that the most important measurements is where the smallest part of the clothes hit.

  2. love how much effort you put in this!
    just a silly question, to be sure: where exactly is "waist" considered to be? Smallest measurement around the belly (= natural waist) or is the waist measured around the bellybutton?

    1. I asked for the natural waist measurement, so the smallest part around the belly about 1-2 inches above the belly button. :)

  3. Count me as someone who always assumed that most women had underbust larger than their waistline. In my case, I'm overweight and carry quite a bit of weight in my belly area, but my waist is still a good inch smaller than my underbust. So, I guessed the difference would be much larger in slimmer women and women with a more defined waist. Interesting to see that it doesn't always work that way.

    1. I think it's a fairly natural assumption, especially if you have a natural "Disney Princess" build. Most women you see in the media always have the nipped in waist so it's more of what you're exposed to in that sense too. It does appear that once you get under a BMI of 20 that pretty much all women have smaller waists than underbusts (or at least the same size) so if you were surrounded by women at the low end of BMI it would appear to be the case too.

      But I was also surprised to see as much variation as I did. I know I still very much have a rounded stomach (at the moment it's 2" larger than my underbust) and I wonder if that's something that will ever equal out or not? Looks like there's a good chance that it won't considering I don't plan on going to the low end of my BMI range...

  4. Caught this article that Bras 4 Justice linked to on FB. Dunno if you saw it. What is interesting is that it mentions a study that is apparently ongoing at Portsmouth University.... http://www.dailymail.co.uk/femail/article-2115183/So-thats-bras-fit-We-sent-32C-model-bra-shopping--needed-different-size-store.html

    1. Thanks for sharing the link and I agree, it's quite fascinating! Between cup, style, fabric etc bras can vary quite a bit and it makes it difficult to know if a bra will fit perfectly in a given size. I was surprised by how much the model's size changed from going from store to store. I would've expected that she might have to go up or down a cup size but not necessarily into different band sizes as much as she did.

      I really do need to find out more about this study. ;)

    2. June, Did you ever read the full study? I got it from Jenny at the University of Portsmouth (the author of the study). I can provide it if you need it.

    3. No, I wasn't able to download it, if you have a copy please send it to me! Email to: bralessinbrasil@gmail.com. Thanks!!

  5. Wow! I haven't been on your blog for some time and I'm exicted to see what you did:)) It's very interesting! I made quite similar research among polish women about year ago and now I see, that among bigger population results are the same:) I also noticed that sizing offered by Pepperberry doesn't fit exactly everybody and that I should go up with breast size to fit almost all women taking part in my research.

    I also looked into relationship between bust, underbust and waist and I noticed that when waist size goes up, the smallest girth goes up too. So in small sizes the narrowest part of body is waist, while above size 42 its usually underbust. Because of that it's good idea to separate both gorups and to prepare different styles for them.

    Now about the fit and sizing tables - in my shop I'll show table with all main measurements - breast, underbust, waist and hips. I belive that this will enable women to take the best size for them depending on style. The same woman may take different size in different styles, because of her e.g. underbust size:)

    1. urkye- I love it when you make it over here because you always have something great to add! :D

      That's really interesting to hear that you found very similar results with your own studies, I can wait for your clothing line to come out so I can actually see it in action. :)

      Oh, and seriously kudos to you for including more measurements on the garments. It's such a help when ordering online because you get a better sense of what size will fit. Certainly, it's impossible to get a perfect fit for everyone without making custom made clothes, but the closest you can get the better. :)

      Also, please let me know when your line will come out!

    2. hey

      thanks for your sharings!

      when you say size 42... you mean underbust or eu sizing in clothes?
      does anyone know if there is a uk size when a woman start to have bigger stomach then underbust?
      or could that occur in all sizes perhaps except women using bra bands 26,28,30? maybe except 32 too?


  6. http://braslessinbrasil.blogspot.com.br/2012/03/what-curvy-clothes-would-you-like-to.html?showComment=1332282975713#c3577622476263684692

    A very relevant comment from Kinga (BiuBiu). :)

  7. Hello June,

    I had a few questions about your survey!.

    First, I was wondering if you think a certain age group may be more heavily represented in your data or if you got a distribution of a variety of ages: teens, young women, women, older women.

    Second, do you think that a certain distribution of band or cup measurements accessed your blog or was is most likely a random distribution. Meaning, does a certain "stereotype" access your blog/weight loss forum you posted the survey on (example: women with larger cup sizes)? I am wondering this because I find that it is usually women with larger breasts/cup sizes who seek out bra information. Often, women with smaller/firmer breasts do not notice an ill-fitting bra as much as a woman with larger breasts and therefore, does not seek out bra/breast information.


    1. Did you have a chance to see my Part 2: Sample Bias discussion? http://braslessinbrasil.blogspot.com.br/2012/03/underbust-survey-part-2-sample-bias-and.html

      I do think it's somewhat an issue in terms of readers of my blog (most likely women with larger busts). However, I also asked women who are member of a weight loss forum that I belong to and in that case there shouldn't be a particular bias towards a certain band/bust size. Now, it would have been interesting to see what percentage were blog readers and what percentage came from the weight loss forum but, unfortunately, I didn't think to ask that.

      However, my data does match extremely well to data taken from the marines in the 90's and there shouldn't be the same sample bias there.

      Also, I have had a couple of store owners chime in and they have also confirmed my results with their own statistics. :)

    2. Awesome, thanks for answering my questions!

  8. Outlier here: My under-bust has always been around 5 to 7 inches bigger than my waist--even when I'm overweight. No matter how thin I get, my under-bust will not get smaller than 33 inches because at that point it's all bone. This would explain why other women can wear those cute empire waist tops/dresses because of the 1 to 2 inch difference yet I look like a big fat cow when I wear them because of my rib cage! On the other hand, I have always felt ugly because of my abnormally huge rib cage and shoulders but since some are describing it as "Disney Princess" I now feel a little better.

    1. The same here ))
      My ribcage is not less then 32 even if I'm seriously underweight (happend after pneumonia once). I've never been really overweight, so my waist has been always in limits 22-25". 8-10" of difference. No empire style for me too, but in dresses fitted to waist I look gorgeous and I bet so do you. The only trick is to find a seamstress.

    2. Anonymous and malica-dee. I'm sure you both ARE absolutely gorgeous but the struggle is to find clothes that show of your small waists! I agree empire styles really might be major fails for you. One thing that could work, though, is the Porto from Biubiu (if you did want a pseudo empire style) because it's fitted around the midsection.

      However, with more extreme nipped in waist you might want to look more for shirts and dress that show that off. I've seen BiuBiu's Summer City look amazing on Disney Princess' (Thin and Curvy and FullerFigerFullerBust have post posted amazing reviews on it) and BiuBiu is coming out with new versions of it at the end of the month.

      I've also seen women look amazing in the Pinup Girl Heidi. As for shirts. I think the BiuBiu Infinity really flatters nipped in waists very, very well: http://braslessinbrasil.blogspot.com/2012/04/biubiu-lovin-part-3-infinity-36bbbbb.html

    3. Thanks a lot for this advise.
      I have been thinking about ordering stuff from BuiBui something like a month now, but I'm still not sure: if I look on waist-bust measures then I need 34BBBB size (not there! feels kinda weird that even specialized shops don't carry my true size), and I can see that most of their tops fit to the underbust, which is not really good if you have a large ribcage (you don't want people see the real size of your ribcage, it's more flattering when they do bigger breasts assumption ;-) ), so not very much for me there :-(
      But Pinup Girl designs look fantastic, size chart tells me that I will need to take in 5-6" in waist, but since when it really stopped me from buing things?

  9. Blog is good for every one where we get lots of information for any topics nice job keep it up and Pretty good post, this is one of the best articles that I have ever seen! This is a great site and I have to congratulate you on the content.
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  10. I thought I'd chime in. It is very interesting, I have been measuring my waist and underbust as I am losing weight. So far my natural waist and underbust have stayed = or within about .5 inches as I have gone down. (It looks like if the waist is bigger, it quickly goes back to equal within a day or so) But at my heaviest, my waist was a couple inches bigger than my underbust. I am halfway down now. My belly button measure is larger than my underbust, but it is catching up now. It is much much closer than it was even a few weeks ago, and is about 3-4 inches bigger than my underbust.

    So I am no disney princess, but in terms of look? My bust looks wider than my waist by a small amount. Even though those measurements are the same, it is more like >< than ||. It is really interesting. I have noticed that it seems like the only women who reliably look wider at the bust than the waist are the "swimmer" builds. A lot of women look pretty straight in the torso. Those disney princesses are rare. :)

    1. Oh I guess I should comment on my BMI (although I think it is BS). So for me, bust = waist started to occur at BMI 37-ish, but not when it was higher. Then the waist was bigger. So I am probably an outlier for your data, as I am nowhere near BMI of 21. Current clothing size is US 16.

  11. I googled question regarding underbust being smaller than natural waist. It brought me here. I'm so glad I found this. Even at my skinniest I had underbust smaller than waist, and it was hard to shop, especially for dresses. Thank you!

  12. Hi! I know you wrote this forever ago, but I just wanted to mention that it seems for the individual waist measurements graphed that it is actually pretty common for underbust>=waist and that we really only see a bit of underbust<waist as the waist measurement goes up. I wonder if the waist measurements not graphed out could be the reason for the overall result of underbust<waist.

    I think, if that were the case, it would also really be interesting to see a waist vs. underbust graph to see if there would be a more obvious trend than with BMI.

    (also, it seems the 31" waist graph breaks the trend in that the bust measurements are drastically smaller than the underbust measurements. I was wondering if the colors perhaps got switched? If not please ignore.)


    1. Ignore that last sentence in the first paragraph. I misunderstood the results of the first graph (that it is a bit more likely that underbust>=waist). But, I would still be interested to see the results of this graph. Although it would probably make more sense to do a waist vs. (underbust-waist) like you did for the BMI graph.


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