Bra Sizing Tools & Calculators
Free, instant, no sign-up. The same measurements and formulas that drive the size-run conformance registry, opened up so you can run your own numbers against the standard.
Measured Size Calculator
Turn an underbust and a bust measurement into your band and cup in five national size runs — and see exactly how far the legacy +4 rule would have put you out.
Open toolSister Size & International Converter
Enter a size in any run and get the UK, US, EU, French and Australian equivalents plus the full sister-size ladder that holds cup volume constant.
Open toolSupport Requirement Calculator
Work out the peak vertical displacement your activity produces at your cup size, and the percentage of control a construction has to deliver to hold it.
Open tool