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More Dimensions Experiments
Slightly inspired by MilkAndHoney 's series of adventures relating to root width ratios, and also some reading I've been doing on bra pattern drafting has got me thinking. Is there a way of approximating the volume our breasts need? Can we apply the method of approximation to bras? This is a pretty numbers driven adventure, just as a heads-up.
Firstly, I had a shot at measuring the volume of my breasts via displacement. This is easy to do, albeit messy. You need a container large enough to fit your breast in, a measuring jug, and a flat space which you can get wet. I wasn't super satisfied with my results from this, as I feel like the volume I got was noticeably short of what I'd expect (even with the knowledge that I have to size up a lot to get the depth I'd like in bras). I ended up displacing about 2,000 ml of water, which according to Wikipedia is closest to a 28K http://en.wikipedia.org/wiki/Brassiere_measurements . I'm thinking that my methodology mustn't have been quite right, as the most recent bra I tried in that volume was good for height and width, but disastrously shallow.
Browsing that article I saw that they had some calculations for volume of a hemi-ellipsoid as well as a hemisphere. This is definitely something we can apply to bras, and breasts as well! While it's certainly not going to be 100% accurate, it does seem to be a decent approximation. The formula for a hemi-ellipsoid is V=(2 pi abc)/3
where a, b, and c are the radii of the axes of the elipsoid.
So, I grabbed a bra and a rule and started measuring! I took my Panache Jasmine in 30K, and took down some numbers. I'm not sure what the best thing would be to call the different terms, because we already use them in certain ways on bratabase, and they'd be different things in this context. The width of the bra was 17.5 cm (measurement taken excluding wire channels at the widest point parallel to the bra band), the height was 18.5 cm (from base of cup to where the cup joins the strap excluding wire channels perpendicular to the bra band), and the depth was 15.2 cm (from the apex of the bra to the underwire, not the perimeter around the cup as we'd measure on Bratabase). These are basically the axes of our hemi-ellipsoid. Then, with a bit of number magic
V= (2 pi (17.5/2)*(18.5/2)*15.2)/3
= 2577 cc (rounded to nearest whole number)
If we look at the Wikipedia chart, a 30K bra is supposed to hold 2340cc, so this seems to check out. This is still an over-simplification of the shape of a bra, but it seems to give a somewhat accurate result. Being in the size range I am, even small differences in radii will give huge differences in volume, but I don't have smaller bras to measure. I'd love to see how this works out on bras in other size ranges.
I decided to do the same thing for my breasts, though it's quite difficult to get accurate measurements owing to bodies curving and rulers not curving! I got a width of 16cm, height of 15cm and depth of 19cm (whyyyyy??? This clearly shows my fit problems numerically). Using the same formula, I get a volume of 2,387 cc (rounded to nearest whole number).
So, to extend this, there'd be a few questions. Do bras you own seem to fit within the expected amount of volume for your cup size? Do you also find that the measurements of one of your breast axes forces you to take a different size than you'd expect from your breast volume? I'd love to create a little calculator so people could have a play with different numbers, but I'm drawing a blank on the best way to do it.
Edit: I put it in the comments, but just to be easier to find, I've set up a calculator here if you want to calculate volume based on dimensions.
https://docs.google.com/spreadsheet/ccc?key=0Ao1YUOEQgWZ6dHB2eWFRemFkTlE3ZmV1N1A0NnNHeXc#gid=0
Filed under Bra sizing and fit
13 comments
I've done water displacement and thought it worked pretty well. The Wikipedia table put the amount of water I displaced close to my actual cup size, and I was finally able to quantify the amount of asymmetry that I have. I think for me the key was to plunge it in with some force until my collarbone and ribs hit the side of the container, so as to prevent the fact that my breasts float from affecting the result. I then looked at the water remaining in the container with both a measuring cup and weighed it for extra confidence (since liters/cc/grams all line up nicely). I think this works better than trying to catch the overspill and measure that.
This still doesn't tell you shape, of course, but I'm waiting for 3-D scanners to become more available :)
Just commenting here to keep track of this post. Sounds very interesting!
By the way, I'm actually planning to do some more work on those breast ratios soon and I'll certainly keep you all posted.
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