Estimate your bra size in a few quick steps.
Measure snugly around your ribcage, just under your bust. Keep the tape level and parallel to the floor.
Measure around the fullest part of your bust, again keeping the tape level.
Enter both measurements and select the correct units.
Use the recommended band and cup size as a starting point, then check sister sizes if you’re between sizes or want a tighter/looser band.
Sister sizes are bra sizes with the same cup volume but a different band size (for example, 34C ↔ 32D ↔ 36B). They can help you fine-tune band tightness while keeping a similar cup fit.
US and UK sizing systems use different cup lettering progressions. This calculator provides both so you can shop in either sizing system.
Bra sizing varies by brand, style, and personal preference. Recheck measurements, ensure the tape is level, and try sister sizes if you’re between sizes.