Estimated size
—
Band: — cm · Cup difference: — cm
| System | Size |
|---|
Sister sizes (same cup volume, ± band)
| US | UK | EU | JP |
|---|
How the math works
US/UK bands are the underbust in inches rounded to even. EU bands are underbust + 0 in cm rounded to 5. JP uses cm directly. Cup letter comes from (bust − underbust) cm: 1cm per step (AA=10, A=12, B=14, C=16, D=18 in inches, ~2.5cm per step in metric).
Sister sizing: drop one band → go up one cup (and vice versa) keeps the same cup volume. Useful when the band fits but the cup doesn't, or the other way around.