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?
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
If we break down the variance by BMI we then find
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)
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%
- 38B 35.8-37.4
- 38BB 37.8-39.4
- 38BBB 39.8-41.3
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
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
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
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'd love to hear some feedback from clothing manufacturers, how do you deal with these issues?