You may have been told that there would be no math, but unfortunately, there’s a one-in-two chance you might need this particular bit of figuring:
The traditional method reads like an A-level algebra problem. You take a tape measure and wrap it round your chest at the lowest point where a bra sits. You record this figure in inches. You add four to this measurement if the number is even, five if it’s odd — and the resultant number is your band size. Then you wrap the tape round again and measure the fullest part of the actual breasts. Next you subtract the band size from breast size to find your cup size. If the numbers are the same, you’re an A cup. If there’s an inch difference, you’re a B; two and you need a C cup and so on.
For no good reason, I actually knew this much. But my knowledge ended well before this point:
Alternatively, and many bra experts say more accurately, you can weigh your breasts by dunking them into a full bowl of water and measuring the displaced liquid, with 1 litre of water equalling 1kg. It’s accurate but useless. You can do precisely nothing with this information, as no bra manufacturer measures boobs by the pound.
One liter equals about 4¼ cups, but presumably not those cups.
The new European sizing standards (EN 13402), still not implemented as of this writing, retain the cup measurement as we know it, but the band size is specified in centimeters, rounded to the nearest multiple of 5: “36” becomes “80.” I don’t anticipate anyone with more curvature than your average Popsicle® stick being enthusiastic about this.
Still unaddressed: the issue of asymmetry.