I got asked a few weeks ago, whether there are any standard measurements that you can use as a starting point when starting to design, so you achieve the correct bra size.
Unfortunately there are no standard bra size charts, each company does their own bra fitting and designs patterns for their own customer.
However I can give you some insight on measurements from different companies I've worked with and where some companies start.
I have worked with a company (2014) that had their own bra size chart where they begin each bra sample with the underband of a 34B measuring at 64cm andeach wing measuring 16cm and the bra cups with cradle measuring 32cm.
When I design a pattern for my brand (aimed at women with smaller backs and a bigger bust size, so my measurements may be different from high street brands). I start with a pattern/bra that I'm happy with the fit then I use that as pattern block and with every design I use that pattern and alter that, to fit the new style. Usually then, only a few bra measurements alter, depending on the fabrics or how much the design has altered.
Lingerie Specification sheets
Below are actually specification sheets from when I designed for UK high street stores, The first one is from Topshop (2001) and the second is from River Island (2003), originally they were presented with designs that were from the same pattern (different design), and due to how they do their bra fitting on their fitting models, they altered the fit therefore altered the measurements such as on the wing, the underband and also the centre front.
There are no correct or standard measurements for lingerie, and even different companies have different size charts and grade differently (the UK brands grade underbands on 5cm and the French brands grade underbands on 4cm); so even if you start at the same measurements by the time you reach 4 sizes bigger or smaller then each brand measurement will be different. The best thing you can do is stay consistent to your own brand, each bra fits each woman differently so what is favourable by one person may not to be so in another, so build your brand with your core customer in mind.
*For those who need advice on How to fill in a Specification sheet then the book "how to spec a bra and brief" is available to download or buy as a book. Also there are downloadable spec sheet that you can use as a template.