A free, independent tool built to make finding your correct UK bra size straightforward.
Most people have never had a professional bra fitting, and a huge number are wearing a size that no longer fits — or never did. We built Bra Size Calculator UK to make finding an accurate starting size free, private, and available in under two minutes, without needing to visit a shop.
Our calculator uses the direct-measurement method: your underbust measurement (rounded to the nearest even number) gives your band size, and the difference between your bust and band measurements gives your cup size. This is the method used by most UK lingerie specialists today. It differs from the older "add 4 or 5 inches" formula described in some traditional NHS trust guidance — we explain both methods, and why they can give different results, in our how to measure guide.
Every size chart and conversion table on this site is checked against the same UK band-and-cup convention used throughout the site, and reviewed periodically as fitting standards evolve.
Content is written and reviewed by the Bra Size Calculator UK team, cross-checked against published sizing guidance from UK retailers and NHS trust patient information where relevant. Every guide carries a "last reviewed" date so you know how current the advice is.
Spotted something inaccurate, or have a suggestion? We'd like to hear from you — see our contact page.