Bra Size Calculator
Enter your values below and click Calculate for instant results.
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Estimate your bra size from band and bust measurements. Includes cup size guide and fitting tips.
Enter your values below and click Calculate for instant results.
Accurate bra sizing requires two measurements taken with a soft tape measure. The band measurement is taken directly under the bust, snugly around the ribcage. The bust measurement is taken at the fullest part of the chest. The difference between these two measurements determines the cup size.
Bra sizing varies significantly between brands and countries. US sizing (32A, 34B, etc.) differs from UK, EU, and AU sizing conventions. This calculator uses US sizing. A 34B in US sizing corresponds roughly to a 34B in UK, 75B in EU, and 34B in AU sizing, though cup volumes can differ slightly.
Sister sizes are bra sizes that contain the same cup volume but different band and cup size combinations. A 34C has the same cup volume as a 32D and a 36B. If a 34C fits in the cups but the band is too tight, try a 36B. If the band is too loose, try a 32D. Understanding sister sizes makes it easier to find a comfortable fit across different brands.
The band should feel snug but not painful, sitting horizontal around the back. The underwire (if present) should lie flat against the ribcage, not on breast tissue. The center gore should lie flat against the sternum. Cups should contain all breast tissue without spillage. Straps should not dig into shoulders, which often indicates a band that is too loose.