Underbust Survey - Part 4: Bust Variation

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

I've finally had a chance to  write up Part 4.  My apologies for being slow commenting but these things take a lot out of me and I just really needed a break from blogging for a couple of days.  I'm hoping to catch up on answering all the comments now. :)

Bust Variation

One thing that I wanted to study too was how much bust size varies depending on how you choose to measure it. In my survey I gave four methods for measuring your bust size:

• Perimeter of one breast
• Bust measurement taken standing
• Bust measuring taken leaning forward (with a bra on)
• Bust measurement taken laying on your back

I noticed in my results that for the Perimeter of the breast I think a few ladies might have gotten confused and measured the perimeter of BOTH their breasts, not just one.  However, I have included all my results in percentages and as you can see below those did not contribute much at all.

In terms of usable results, I had significantly less compared to previous posts, simply because not every women knew all their various measurements. With the exception of two responses, I always received Bust measurement taken Standing so my results are all based upon the variation of the other measurements from that.  Thus, I had the following number of respondents give me enough information to calculate (that is to say they provided me an underbust measurement, Standing Bust measurement, and a second type of bust measurement in at least one of the following categories):

• 129 responses for Perimeter-Standing
• 129 responses for Bent forward-Standing
• 131 responses for Back-Standing

All that leads to the following graph:

What I find quite remarkable is that when a woman takes her bust measurement laying down on her back compared to her bust measurement standing that they are almost always identical (64% are the same and 82% are within a range of +/- 1 inch).  Comparing the perimeter of one breast to the standing bust measurement we see the larger range of the distribution (although there's still a relatively narrow peak between 0 to +2 where 65% of the responses fell in that range), although again I wonder if there was some confusion about that particular measurement.  Finally, when comparing the bent forward bust measurement to standing we see a much wider peak that is centered around 0 to +3 (90.7% of the responses fell in that range).

So what can we take away from this?

• Measuring on your back vs. standing are almost identical, so if a woman is not getting the correct cup size from her standing measurement then it's not likely she'll get the correct measurement from laying on her back either.  Then again, it could be that the 36% of women  who didn't get identical measurements from back vs. standing need to just go up or down 1 cup size.  
• Measuring the perimeter and measuring leaning forward have a much higher percentage of variation.  Not surprising because my guess is that women who have softer breast tissue are going to see a larger variation when they lean forward.  I wish I would've asked the age/pregnancy, breastfeeding, and weight loss history of participants and see if there was a correlation there. 

Now the question remains, which measurement correlates best to cup size?  I honestly don't know.  When I took my own data point of as a test I found the following:

My measurements are:
Underbust- 28"
Bust Standing- 39"
Bust on Back- 39"
Bust Bent Forward without Bra- 42"
Bust Bent Forward without Bra- 40"
Perimeter- 12"

which leads to following differences:
Perimeter- 12"
Bust Standing- 11"
Bust on Back- 11"
Bust Bent Forward without Bra- 14"
Bust Bent Forward without Bra- 12"

that corresponds to the following sizes:

Perimeter- 28HH
Bust Standing- 28H
Bust on Back- 28H
Bust Bent Forward without Bra- 28JJ
Bust Bent Forward with Bra- 28HH

By all my best estimates I'm a 28J, possibly even a 28JJ (granted, this also depends on the time of the month).  I also have asymmetric breasts -as do most women- where one seems to be more of a 28HH, the other is a 28J on my "small days" and my "large days" it's probably more like 28J and 28JJ.  So all that is to say that my measurements seem to fit somewhere between Perimeter/Bent forward with a bra and Bent forward without a bra.  Possibly if I had a 28J bra then my bent forward with a bra would converge towards my bent froward without a bra.

Now, I have soft breasts, would the best measurements change for some who has firmer breasts?  What about a women who has more wide-set breasts? Or lots of breast tissue migration? 

As I mentioned in Part 3, I imagine a study where women were measured and fit in person would be a better approach.  In this case, the variance could be easily measured in lingerie shops because even if it does vary by cup size or there is some sort of sample bias, it wouldn't matter as much because the shops could build meaningful statistics for their target customers.

My gut feeling is that the standing bust measurement is difficult to get correct unless a woman is already wearing her correct bra size.  A bra with a band that is too large and cups that are too small will lower the breasts so you're not measuring all of your breast tissue when you measure.  You can see the difference here (sorry for the crappy drawing!):

I did ask for bra sizes in my survey but many women were not wearing bra sizes that corresponding to their underbust and many others didn't know their bra size at all so it would've made statistics difficult.  I didn't know if they were wearing that size because it actually fit or they didn't have any better options.  Again, this is one weakness in a online study because it's not something that I can judge over the internet.