the plus four debate – a word is elegy to what it signifies

For part two of my exploration of the bra, an in depth look at the bra band, its relationship to cup size, and its role in complicating everything about finding a bra that fits.

The bra band is really the base of the bra. It’s where the vast majority of the support comes from, and the support it provides is cantilevered horizontally from the close fitted band and the cups holding the weight of the bust up, rather than support by suspending weight from the shoulders, which hurts and doesn’t work very well.

vertigo cantilevered bra — Oh, yes, Jimmy, it is a veritable marvel of modern engineering.

The bra band also establishes circumference of the torso at the underbust (for simplicity, I’m disregarding for a moment the way that the old plus four inches issue muddies the waters for certain sizing systems). Bra band size is the starting point for how we describe bra sizes. Cup sizes are relative, and the letters actually have no meaning without a bra band to give them context. Even though we talk about double Ds or B cups as if they describe an objective size, they actually don’t mean anything, because they are relative to the band size that defines them. Here’s a better visual explanation of how cup size relates to torso/band size:

The way that we write bra sizes as a numerical value and a letter is kind of like a little math equation where the bra band is the base circumference of the body at the underbust, and each letter increase adds an inch to this to end up with enough room for the circumference of the bust at the fullest point:

AA = .5 inch

A = 1 inch

B = 2 inch

C = 3 inch

D = 4 inch

DD or E = 5 inch

And upward, though the specific letters used sometimes vary from manufacturer to manufacturer or European system versus American sizing system, etc. If you wrote it as a math problem, it would be something like this:

Numerical band size/underbust circumference + letter to specify extra cup inches = full bust circumference

So for a 36B, it’s basically an equation that says: 36″ rib cage + 2″ total added in the cups = 38″ full bust measurement. This is why sister sizing works, where you can go down a band size but a cup letter, or up a band size and down a cup letter, to approximate a fit like your exact size (more on this another day).

This sounds simple enough, but then everything gets complicated, because A) different fabrics are reduced by different amounts depending on stretch and recovery properties, so a band designed for a 36″ rib cage probably will measure smaller than that, B) all bodies are not the same and the broad backed and non-standard torso-ed among us (*raises both hands*) are statistical outliers who can’t find an appropriate size this way, and C) the plus 4 phenomenon.

The plus four thing is an often repeated piece of advice bra fitting – take your actual rib cage measurement, if it’s even, add four inches, and if it’s odd, add five inches to get your band size. To me, this seems illogical and stupidly complicated, and it seems more intuitive to just use your actual rib cage measurement. There are interesting historical reasons that this developed that I’m reading up on and will write about, but it seems to have been a vanity sizing tick that happened around the ‘50s or ‘60s when bra sizing as we now know it began to emerge as an industry standard. Things get really, really complicated these days, because sizing standards vary by market (American, UK, EU, Japanese, Australian, to name a few), and because in the US market, some companies no longer add these inches into the band sizes, and some companies do. This means a 36 band brand A might not be drafted for the same rib circumference as brand B, so your 36B is not the same size across brands. For those of us who don’t want to try on 37 bras at the mall to find one with a good fit, this is exasperating.

This isn’t exactly the bra manufacturer’s fault, since it is very hard to accommodate the wide range of bust shapes, sizes, and body proportions that exist in the real world into a single approximation. It’s a complicated supply/demand and consumer knowledge problem. Even if there were more variations available, most of us (my pre-lingerie-addiction self included) would not know where to begin to understand our particular shape and support needs. That being said, some kind of standardization on band measurement seems to me like it would make it much easier for all of us. (In my own drafting and bra sizing, I use an exact rib cage measurement as a starting point, since the plus four model assumes a certain standard tapered rib cage typical of more of an hourglass shape than the vast majority of women have. Statistically most of us are much more rectangular.)

I’ll be rambling about bust position next in my sprawling Ted talk on the mechanics of the bra. 🙂 I’d love to hear any thoughts, and if anyone knows more about the weird history of bra size standards, I’d love to hear more on this.

I’m excited (and a bit jittery) to say that my Etsy lingerie shop is finally open. I’ve been setting it up for a few weeks and still have *so many things* I want to add to it, but it’s a start that I feel proud of. Also excited to say I’m testing sizing and writing up directions for a sewing pattern I hope to release soon. The crafter life goals of sewing for others and pattern drafting do work well together.

So far, no full cradle bras because I’m writing up my 95 theses of how to fit a bra. Not really 95, but a few pages for sure. I’ve been reading a lot on sizing standards and the history of different measurement practices and vanity sizing, and now I see why most of us are totally confused by manufacturer sizing. More on this later when I get my fitting guide all hammered out, but the issue of adding four or five inches to your underbust measurement really throws a wrench in everything. What’s even more frustrating is that just using your raw underbust measure seems like it would clear up everything, but then you have to grapple with figuring out which manufacturers add inches to the underbust measure for their bands and which don’t, and with how individual brands approach sizing, because a 36B in one brand might be another brand’s 32DD. (I intend to use the raw underbust measure, myself, though I’ve found the high bust to be a better place to measure – right under the armpits, over the bonier part of the upper chest, since the underbust measure can vary so dramatically with breathing, sitting vs. standing, bloating, etc. It tends to be slightly larger than the underbust measure by an inch or two, which works out perfectly for me with my broad back and unusual proportions, but may not for everyone.)

For now, I’ve focused on lacy bralettes, underwear and garter belts in the shop, and I’m still learning the ins and outs of SEO and writing copy and it’s been actually kind of amazing in researching all of that to realize how much snake oil marketing stuff floating around out there is promising starry-eyed budding entrepreneurial dreamer types like myself that a fortune is there for the taking if we just fork out 2k for whatever guru’s online course! Ugh, gross. (They tell me that if I don’t set up a mailing list, the howling abyss demon of failure and loneliness and bad skin will come for me, so if you’d like to join the mailing list, it’s (here), and I did set up a 10% off code that will be sent to your email, and I promise I won’t spam you. Especially not with false scarcity marketing or canned enthusiasm adspeak crap, because the world has more than enough of that.)

Learning photography is infinitely more fun, though I think I lost at least a week to cussing my camera controls and my cat for jumping in the shot when I finally got all the elastics to lie flat for two seconds. You can really see the eternal conflict between my antique feminine, Marie Antoinette delicate aesthetic and my Morticia Addams for life/what would Cersei wear sensibilities: