Bra size calculator in cm (EU method)
The European method works straight in cm: the band comes from the underbust and the cup from the gap between the two.
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How to use it
- Enter underbust and bust.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Band = underbust rounded to the nearest 5 cm (73 to 77 = 75). Difference = bust minus underbust, and each cup spans 2 cm: AA 10 to 12, A 12 to 14, B 14 to 16, C 16 to 18, D 18 to 20, E 20 to 22.
Example
Inputs: Underbust = 75 cm, Bust = 90 cm. Result: EU size: 75B; French size: 90B; UK size: 34B.
Limits and caveats
- Values right on a cup boundary go to the larger cup, so try both.
- UK and US equivalents come from the usual conversion chart and may differ by one cup.
Questions about this tool
Why is the gap taken from the underbust, not the band?
That is how the European system defines the cup: bust minus underbust in cm.
How many cm is each cup step?
2 cm in EU sizing, compared with 1 inch (2.54 cm) in UK and US sizing.
My underbust is 72 cm. What band is that?
70, because 72 is nearer to 70 than to 75.