40 US/UK band sizes to French band sizes

How to convert 40 US/UK to FR/ES/BE

FR/ES/BE = US/UK × 2.5 + 5

1. Take the value: 40 US/UK.
2. Multiply by 2.5: 40 × 2.5 = 100.
3. Add 5: 100 + 5 = 105.
4. So 40 US/UK = 105 FR/ES/BE.

Sizes come in steps of 5, so the nearest French band size size is 105. This converts the band (number) part of a bra size only. Cup letters also differ between systems (for example, US DDD is UK E), so check the brand's chart for cups.