Most women wear the wrong bra size. If your underbust is 65 cm (25.5 inches) and your bust is 90 cm (35.5 inches), you indeed need a 65G. But many women with similar measurements wear 70D or 75C — which will gap at the band or spill at the cup.
This indicates an underbust measurement of approximately 63–67 cm (25–26 inches), which is typical for a very petite or slender build. 65g cup korean women 1
A "G" cup in Korea typically represents a difference of approximately between the underbust and the fullest part of the bust. International Conversions: int.triumph.com Demographic and Cultural Context Average breast size worldwide - Worlddata.info Most women wear the wrong bra size
A 65 band is quite small, typically fitting a woman with an underbust measurement of approximately 63–67 cm. In US/UK sizing, this is equivalent to a 30 band . In US/UK sizing, this is equivalent to a 30 band