Bra Math, Sister Sizing and rubber bands?

If you’ve read my “About Me” page then you might remember that I talked about the last time I went shopping for bras before my fit training started. It was a 2-3 hour affair that ended with me buying a couple of size 38B bras. They seemed the best fit at the time but it never even occurred to me to try a 34D. I was conditioned my whole life to think of D cups as only for large busted women. I had always shopped in the “barely there” sections and after kids I wasn’t much bigger! Here I want to say that most fitters that have been trained in the mysteries of sizing are not out to fit shame anyone about how their bras fit, especially not me. This is a judgment free zone. If you’re happy where you are then that’s all that really matters. BUT, if you’re unhappy and frustrated by fit and sizing then there is help. It just really doesn’t lie in online size charts for most women. It’s simply more complicated than that. Learning some of the secrets of fit might not be life changing for everyone but it literally changed the way I buy my clothes and how I look and feel in them. Just as my kids were hitting their stride, learning this skill felt like reclaiming a part of myself from motherhood. So in this limited space let me see if I can shed some light on the topic. I hope it will encourage you to reach out and connect to find out more.

So here we go... using my size as an example I learned that in cup “volume” I was actually in the right ballpark with my 38B. Think of the cup as holding liquid. You’d be able to put about the same amount in a 38B, 36C, 34D and 32E. Now imagine the liquid is frozen. The 38B is going to be bigger and flatter and the 32E is going to be smaller but thicker. Sister sizing is about rearranging the fabric of the bra and the shape of the wire. I would always tell people to imagine a bra as thick rubber band. When you stretch it, the whole bra gets wider (including the straps that are always falling off your shoulders) and the cups get more shallow. The wire shape is also smaller which is often why they always seem to dig and poke. Conversely, if you shrink the band, the cups get taller and deeper. The wire gets bigger as well. This is how I could take 4-6 inches off the size of my 38B and go to wearing a 34 or 32 band and not feel uncomfortable. Instead of squeezing the breast tissue into the band you are basically providing a bigger parking spot. This is how you get lift and support. I was wearing a bra that was 6” too wide for my frame. No wonder my straps always fell down and it moved around all day! When I got into the correct size if was such a relief not to mess with my straps all day anymore!

So the basic secret to “bra math” is that for every 2” you subtract in the band you add one size in the cup. If someone is wearing a 40D because that gave them the volume in the cup needed but is measuring say 34” they should be wearing something closer to a 34G which is really a pretty average size though not available in most stores. Some stores go to G and H cups so someone might be wearing a 38G for example but have a rib cage that measures 32”. They might get a much better fit in a 32J. These are ballpark examples because so many brands vary in fit and size range. This is why a professional fitting can be so beneficial and why it can be so hard and confusing to try to use online fit calculators. This is also where I can help!

If your curiosity is piqued (and I hope that it is!) I hope you’ll connect with me for more information about your specific concern. The most commonly cited statistic is that 80% of women are wearing the wrong size which creates frustration and probably a fair amount on back pain and skin chafing. I want to help lower that percentage. The consulting is free at this time and if budget is a concern then I can direct you to the most budget friendly options if you’re ready to try something new! 🌼🌼

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