Bra Size Calculator

US band and cup estimate from underbust and bust (inches or cm).

Bra Size Calculator helps you uS band and cup estimate from underbust and bust (inches or cm). Enter underbust and bust, review the breakdown, and use the guidance below to understand what the number means — and what it does not. What the Bra Size calculator does Bra Size Calculator is built for everyday questions — shopping, home, travel, hobbies, and tech. US band and cup estimate from underbust and bust (inches or cm). You enter underbust and bust, then Simple Calculators computes the result instantly. Defaults are chosen to be easy to read — change any field to match your situation. How the math works Pick Units, then enter your Underbust (snug around the ribcage, just under the bust) and Bust (around the fullest part). Centimeters are converted to inches first. The band is the underbust rounded to the nearest inch, then bumped up to the next even number. Each inch of bust minus band is one cup size: 1 in = A, 2 in = B, 3 in = C, 4 in = D, and so on. The formula: Band = underbust rounded to an even inch; cup = bust − band (1 in per cup). Measure snugly under the bust for the band and around the fullest part for the bust.