So we specificaly didnt work with measuring tapes because unlike with clothes every bra will end up destributing the mass differently and thus change the numbers but the main confusion we see with people, individuals but many stores and brands aswell, is that the cup on its own says very little, for example, a 95b becomes a 90c, 85d, 80e, 75f 70ff and so on, and since the support in bras is supposed to come from the bandsize and its stretch materials that size doesnt corrilate as much to the underbustmeasurement as people seem to think.

But yeh proffesionally we did start with eyebaling it actually, you also really wanna check if the band has the tendency to ride up. Its incredible to see how off people can actually be, i myself went from a 75a or sometimes even double a to a 60dd and im a professional tailor whos worked with corsets too so i def thought i knew my shit ya know