Find your best-fit bra size in US, UK, EU and international sizing.
About This Tool
This calculator estimates bra size from under bust and over bust measurements. Results are a starting point—fit varies by brand. All data stays on your device.
How to Measure
Wear a lightly lined, non-padded bra or no bra.
Under bust: measure snugly under your breasts, level around the ribcage.
Over bust: measure around the fullest part, keeping the tape level.
Enter both values, choose cm or inches, and review all regional sizes.
Round to the nearest 0.5 cm or 0.25 in. Stand straight and breathe normally.
Size Tips
Band riding up? Try a smaller band and larger cup (sister size).
EU band numbers are centimeters (75, 80); US/UK bands are inches (34, 36).
UK and AU/NZ cup letters differ from US above D cup—check both columns.
Always try bras on; sizing varies especially at fuller cup sizes.
Calculate Your Size
Enter your measurements to see your estimated sizes.
Suggested US size
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Purchasing tips
Hook a new bra on the loosest row—the band will stretch with wear.
The center gore should lie flat against your sternum (underwire styles).
Scoop all tissue into the cup; wires sit on the ribcage, not breast tissue.
Sister size: one band down + one cup up (e.g. 34C ≈ 32D) keeps similar volume.
Sports, balconette, and plunge cuts fit differently—use this as a starting point.