Bra Size Calculator (Band & Cup)
Band and cup from underbust and bust measurements using the modern (no '+4') method, with sister sizes.
Modern fitting drops the old 'add 4 inches' rule — band equals snug underbust. Cup letters only mean anything relative to a band: a 75D holds the same volume as an 80C or 70E ('sister sizes', shown above). Across brands, fit beats arithmetic: this is a starting point for trying, not a verdict.
Formula
For general information only — not medical advice, a diagnosis or a treatment plan. Consult a qualified healthcare professional before making health, diet, medication or exercise decisions.
Band and cup from underbust and bust measurements using the modern (no '+4') method, with sister sizes. The Bra Size Calculator (Band & Cup) is a free, private bra size calculator tool — every result computes instantly in your browser with no sign-up and no data upload.
About Bra Size Calculator (Band & Cup)
Modern fitting drops the old 'add 4 inches' rule — band equals snug underbust. It applies band = underbust rounded to 5 cm; cup = bust − underbust (2 cm per letter from ~10 cm). Use the Bra Size Calculator (Band & Cup) to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Bra Size Calculator (Band & Cup)
- 1Enter your details in the Bra Size Calculator (Band & Cup) input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Bra Size Calculator (Band & Cup)?
- ✓Instant bra size calculator result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (ISO 8559 anthropometric definitions)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Bra Size Calculator (Band & Cup) work?+
Modern fitting drops the old 'add 4 inches' rule — band equals snug underbust. The calculation uses the formula: band = underbust rounded to 5 cm; cup = bust − underbust (2 cm per letter from ~10 cm). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Bra Size Calculator (Band & Cup) accurate, and what is it based on?+
The method is traceable to authoritative sources, including ISO 8559 anthropometric definitions; McGhee DE & Steele JR, J Sci Med Sport 2010 — bra fit research. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Bra Size Calculator (Band & Cup) free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is for general information only and is not medical advice. Always consult a qualified healthcare professional before making health decisions.
What can I use the Bra Size Calculator (Band & Cup) for?+
It's commonly used for bra size calculator, cup size, band size. Band and cup from underbust and bust measurements using the modern (no '+4') method, with sister sizes.
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