Lifestyle
Bra Size Calculator
Find your US, UK, and EU bra size from your underbust and bust measurements, plus sister sizes for a better fit.
Your measurements
Enter your underbust and bust measurements. Bust must be larger than underbust.
Frequently Asked Questions about the Bra Size Calculator
How do I measure for a bra size?
Wrap a soft measuring tape snugly around your ribcage directly under your bust and note the underbust number. Then hold the tape loosely across the fullest part of your bust, keeping it level all the way around. Enter both measurements in inches above. The calculator rounds your underbust to the nearest even number to get your band size, then subtracts the band from your bust measurement to find your cup.
What are sister sizes?
Sister sizes share the same cup volume on a different band. If a 34C band feels too tight, try a 36B - the cup holds the same amount of tissue but the band is 2 inches larger. If the band is too loose, try 32D instead. This calculator shows both adjacent sister sizes in the results so you can compare.
Why does the same size fit differently across brands?
Bra sizing is not standardized across manufacturers. Band elasticity, underwire shape, and cup depth vary by brand, so two bras labeled 34C can fit a full cup size apart. Treat your calculated size as a starting point and try several brands before settling on one.
What if I am between sizes?
If your bust measurement falls on a half inch, the calculator rounds to the nearest whole inch for the cup difference. Try the resulting size first - most bands stretch slightly with wear. If the band rides up in the back, move to the sister size with a smaller band and larger cup.
Why does my US size not match my EU size in numbers?
US and UK bands use inches (32, 34, 36) and share the same band number, so a US 34 and UK 34 are the same band. EU bands use a standardized centimeter scale from a conversion table, so US 34 becomes EU 75. Cup letters also diverge above D: US DD is EU E, US DDD is EU F, and so on - which is why a US 34DD equals a UK 34DD but an EU 75E.
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