Bra Atlas

About Bra Atlas

A bra sizing reference built on one engine. Every size, conversion and sister size on the site comes from the same tested code, so the calculator, the charts and the size pages can never disagree with each other.

Who makes it

Bra Atlas is built and maintained by Rai Ansar, a software developer. It grew out of a sizing site drafted by a partner who will be writing more of the fit content; the calculators were rebuilt from scratch around one tested engine.

Neither of us is a professional bra fitter, and the site does not pretend otherwise. Where it gives fit advice, it cites the research it comes from. Contact: hello@braatlas.com.

How pages are made

  • The engine. One TypeScript module computes every size on the site: the measured-band method, the traditional +4 method, the six label systems and sister sizes. The full method is on the calculator page.
  • The tests. On 25 September 2026 we submitted 18 measurement pairs to the A Bra That Fits calculator in six systems and recorded 10 pairs from calculator.net. Over 130 automated tests pin our engine to those recorded answers; the raw outputs are kept with the code.
  • Brand charts. On 26 September 2026 we opened Victoria's Secret, ThirdLove, Wacoal, SKIMS, Marks & Spencer and Freya size pages in a browser, saved their text, and typed six to eight tape measurements into the Wacoal and ThirdLove calculators. Tests check the brand page against those captures; where a brand's chart disagrees with ours (Freya's Australian letters), the page says so.
  • Sources. Every outside fact links to where it came from, with the date it was checked. Where sources disagree (Japanese and Australian cup letters, EU cups), the page says so.
  • Search data. Monthly search counts come from Google Ads data pulled through DataForSEO in September 2026.
  • AI use. Page drafts and code were written with the help of an AI model (Claude, by Anthropic). Every number was produced by the engine or copied from a linked source, and the claims were checked against those sources by Rai Ansar.
  • Dates. The "checked" date changes only when sources are re-opened or numbers change.

Money

There are no ads on the site. Size pages carry Amazon Associates search links ("Shop [size] bras on Amazon"), added 26 September 2026 once the Amazon Global Earning tracking id was created. Every link is labelled as an affiliate link next to it, opens a plain amazon.com search for that size (not a specific product we picked), and never changes the size the calculator shows. The Bravissimo, Wacoal, ThirdLove and Marks & Spencer slots described in our code are still unjoined; if one of those goes live, this page and the privacy page will be updated first.

Sources

Each source was opened and checked on 25 September 2026. Where sources disagree, the page says so instead of picking one silently.

  1. A Bra That Fits calculator (community calculator of r/ABraThatFits): we submitted 18 measurement pairs in 6 systems on 25 September 2026; raw output is in our repository
  2. calculator.net, Bra Size Calculator: 10 measurement pairs run in a browser on 25 September 2026
  3. Wikipedia, "Bra size": UK and US cup ladders, the +4 method, EN 13402 and JIS cup steps
  4. White J, Scurr J. Evaluation of professional bra fitting criteria for bra selection and fitting in the UK. Ergonomics 2012;55(6):704-711: 45 women; the traditional method overestimated band and underestimated cup