Bra Size Calculator
Find your bra size from two measurements and convert it between US, UK, EU, French, Italian and Australian sizes.
How to measure
- Underbust: wrap the tape snugly around your ribcage right under the bust, level all the way round.
- Bust: measure loosely around the fullest part of the bust, standing straight, wearing a non-padded bra.
How the size is calculated
The calculator follows the European standard: the band is the underbust rounded to the nearest 5 cm, and each cup letter is a 2 cm (about ¾ in) step in the difference between bust and underbust – A at 12–14 cm, B at 14–16 cm and so on. The band and cup are then converted to the other systems.
Example: underbust 29.5 in (74.9 cm) and bust 36 in give a difference of 16.5 cm – 34C in US and UK sizes, 75C in EU sizes and 90C in France.
Sizes differ between systems
From DD upward, US and UK letters part ways: a US DDD (also sold as F) is a UK E. French and Spanish bands are the EU band plus 15. Brands also differ, so treat the result as a starting point and use the sister sizes if the band feels too tight or loose.
Frequently asked questions
What is a sister size?
A size with the same cup volume on a different band: one band down and one cup up (32D for 34C), or one band up and one cup down (36B).
What is 34C in European sizes?
75C in EU sizes and 90C in French sizes.