The short answer to this question is “no”. Bespoke bras, or custom-made bras, are made to a client’s particular measurements. A good custom bra maker will only be concerned about your unique measurements and proportions.
Let us start by saying that each of us has different measurements and proportions. No two people will have identical measurements and proportions. This is true even for fashion models. That is why for haute couture collections, a garment is fit to a specific model.
You can see examples of this in the excellent film “Valentino: The Last Emperor” by Matt Tyrnauer. One instance in the documentary relates to a hairdresser suggesting to Valentino that two models be switched for a dress because Valentino didn’t approve of the model’s hairstyle. Since the dresses were already fitted and sewn, a change like that would be unacceptable—that is why Valentino refused doing the switch.
You may think that if we all have different measurements and proportions, how is it that ready-to-wear designers can manufacture clothes? The answer has to do with the type of customer that the manufacturer is targeting. If a bra manufacturer is targeting a younger customer, then chances are that the sizes may be limited to a smaller range. But this is not always the case. Usually, a manufacturer makes a sample garment to fit a specific model that they use. Once any problems related to the design and manufacture are corrected, that pattern is graded up for larger sizes, and graded down for smaller sizes.
Since the world of ready-to-wear has changed dramatically in the last several decades, a lot of steps that used to be done to ensure better customer satisfaction are no longer done. We now live in an age where profit trumps quality and fit, and contrary to what most people think, the attitudes and spending patterns of consumers have been a major reason for this. To better understand how the sizing of ready-to-wear works and all its related issues, I highly recommend these articles on The Fashion Incubator. Kathleen Fasanella gives an excellent insider’s view of how the manufacture of ready-to-wear clothing has changed.
In the world of bespoke bras, a ready-to-wear size conveys little meaning because the size depends on the bra manufacturer and what they think a woman’s body would look like with breasts of a particular size. You can be sure that both the bra size and your body’s proportions most likely don’t match.
Even if by a remote chance, you found a well-fitted ready-to-wear bra, that bra size will not be appropriate for you all your life. Why would it be? Your body is changing over time. A lot of people think this is predominantly about aging, but that is only one small part of the change process.
If a woman becomes ill for an extended period of time or takes medication, her body measurements will change. If a woman is on the birth control pill, her body measurements will change and her breast tissue density will change. If she becomes pregnant, her body measurements will change; this is true whether or not she carries the baby to term. If a woman smokes or abuses her body in some other way, that will affect her body measurements and tissue density. If she is on diets and has noticeable weight fluctuations, that will affect not just body measurements but also the skin elasticity. If a woman is doing weight training exercises, her body measurements and tissue density will also change.
So whatever bra size a woman may think she is, she will not be that size her whole life. In fact, the fit of all garments will change during a person’s life. That is why a custom bra maker needs to measure a client at least once a year, and why ready-to-wear bra sizes are irrelevant in the world of custom bras.