[danim]

As you know: 2.54 cm = 1 inch (http://www.convertunits.com/from/cm/to/inch)

Is it true that you need a 13 cm (5 1/8 inch) difference between underbust and bust to be an A ?

Cups
B = 13 + 2,54 (15,54 cm or 6 1/8 inch)
C= 15,54 + 2,54 (18,08 cm or 7 1/8 inch )
D= 18,08 +2,54 (20,62 cm or 8 1/8 inch)
DD= 20,62 + 2,54 (23,16 cm or 9 1/8 inch )

What do you think ??

It is not a fixed law, because it depends also on the shape and fullness etc, but it is a useful orientation. And for me with 16cm difference bust-underbust, I am not bigger than a B, so the chart is true for me. But I read on this forum some girls claim to be a C with only 8-10cm difference, which I however find unlikely, but it is possible that you reach a B before 15cm difference or even need more than 15cm and the same thing goes for an A too, maybe you will reach it before 13cm. for me 13cm difference did not look big at all, but it definitely sounded big and a lot before I have reached it.

I don't find bras more reliable to measure the size, because it depends on the style, padding, brand etc. Very often a B cup from one brand is a lot smaller than from some others and also even from the same brand some styles simply turn out smaller

Rateset, Thanks for all the detailed information. 10 cm is a lot and that's what I need to become an A.