Bra Size Calculator
Use your underbust and bust measurements to estimate your bra size in US, UK, and EU systems. It also shows nearby sister sizes if you need a tighter or looser band fit.
Measure snugly around your ribcage, directly under your bust.
Measure around the fullest part of your bust while keeping the tape level.
How to Use
- Choose inches or centimeters.
- Measure snugly around your ribcage just below your bust and enter that as your band measurement.
- Measure around the fullest part of your bust and enter that as your bust measurement.
- Review your estimated US, UK, and EU sizes, then compare the suggested sister sizes for fit adjustments.
Frequently Asked Questions
How accurate is a bra size calculator?
A bra size calculator is a useful starting point, but fit can still vary by brand, style, and personal comfort. Use the result as a baseline, then adjust after trying on bras if needed.
What are sister sizes?
Sister sizes keep a similar cup volume while changing the band size. For example, if your usual band feels tight, you can go up one band size and down one cup size for a similar fit.
Why are US and UK bra sizes different?
US and UK sizing use different cup naming systems after D and DD. That is why the same measurements may show a different cup letter depending on the regional size format.
Should I measure in inches or centimeters?
Either is fine. This calculator converts both measurements automatically, so use whichever unit is easier for you.