Bra Size Converter
Convert your bra size between US, UK, EU, AU, and FR — instantly. Also shows sister sizes for a better fit.
Sister sizes (same cup volume, different band)
Sister sizes have the same cup volume — try one if your usual size feels too tight or loose around the band.
How bra sizing works across regions
Bra sizing is split into band size (the number) and cup size (the letter). Both differ across regions:
Band size
US and UK use the same band numbers (32, 34, 36...). EU and FR use band measurements in centimeters (75, 80, 85...). AU uses dress-style numbers (10, 12, 14...).
Cup size
Cup letters diverge after a D cup. A US "DDD" is a UK "E". A US "F" is a UK "FF". Make sure to use the right region's letter when shopping internationally.
Sister sizes
Sister sizes have the same cup volume but a different band. If your usual size feels off, try going up one band and down one cup (or vice versa).
Frequently asked questions
What's 34B in UK sizing?
A US 34B is the same as a UK 34B — the US and UK share band numbers and cup letters up through D. Differences appear at DD and above.
What's 32C in EU?
A US 32C converts to EU 70C. EU band sizes are measured in centimeters of underbust.
How do I measure for a bra?
Measure your underbust snugly (band size) and bust at the fullest point (cup size). Subtract the underbust from the bust — each inch of difference is one cup size up from A.
What's a sister size?
A sister size has the same cup volume but different band size. For 34B, sister sizes are 32C (smaller band, bigger cup) and 36A (bigger band, smaller cup).