👙 Bra Size
40B Bra Size — UK, EU & French Conversion
A US 40B bra in UK, European and French sizing, with its sister sizes. Not sure 40B is right? Measure with the bra calculator first.
US 40B = UK 40B
EU 90B · French 105B
A US 40B bra converts to UK 40B, EU 90B and French 105B. The band number maps on a fixed scale, while cup letters shift between systems above D.
| Region | Size |
|---|---|
| US | 40B |
| UK | 40B |
| EU (Europe) | 90B |
| FR / ES (France, Spain) | 105B |
Sister sizes for 40B
Same cup volume, different band — try these if the band feels tight or loose but the cup is right:
38CSister down
42ASister up
⚠️ US cup lettering above D varies by brand (DD vs E, DDD vs F). Match by the EU/UK equivalent when a brand's letters differ.
All bra sizes → · Bra calculator → · Converter →
What is a US 40B bra in UK and EU sizing?
A US 40B is a UK 40B, EU 90B and French 105B.
What are the sister sizes of 40B?
Same cup volume, different band: 38C, 42A.
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