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Bra Size Calculator
Enter your underbust and bust measurements to get your band and cup size.
Your bra size
—
Band + cup.
| Band size | — |
|---|---|
| Cup | — |
| Underbust | — |
| Bust | — |
Show our math
Enter your figures above to see the step-by-step working.
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How the Bra Size Calculator Works
Bra size has two parts: the band, from your underbust measurement, and the cup, from the difference between your bust and band. Measure snugly under the bust for the band and around the fullest part for the bust. The band is your underbust rounded to the nearest even number; each inch the bust exceeds the band is one cup size (1 in = A, 2 in = B, 3 in = C, 4 in = D, and so on).
So a 34-inch underbust with a 38-inch bust is a 34D. Brands vary, so treat this as a starting point and try sister sizes if the fit isn’t quite right.
band = underbust (nearest even) · cup = bust − band (1 in per letter)
Frequently Asked Questions
How do I measure my bra size?
Measure snugly under your bust for the band, and around the fullest part for the bust. The calculator turns those into a band and cup size.
How is cup size worked out?
It’s the difference in inches between bust and band: 1 inch is an A cup, 2 is a B, 3 a C, 4 a D, and up from there.
Why do sizes differ between brands?
Cup and band standards vary by brand and country, so the same body may be a 34D in one label and a 34DD in another. Use this as a baseline.
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