Hari Ito Lingerie patterns use the BCD (Bottom Cup Depth) measurement to determine your cup size.
This might be confusing if you’re used to RTW sizing. We use a different sizing system, with a specific reason. In confection, vanity sizing is a thing. But, as sewists, we know better ;).
You know you need the size that fits you best, no matter the letter or number that’s on the garment. Good fitting clothes will do so much more for you than the number in the label.
This being said, the BCD system has the same flaws as any other system: it will fit approximately 80% of population. But what if you are part of the 20%? Do you guess your size? Or give up altogether? Well, no, you don’t! There are options. You could mail Liesje (Hello[a]hariitolingerie.com) or you can try a different system.
The BCD system is based on the distance from the fullest part of your breasts, usually where the nipple is, to your inframammary crease.
The size could be different for each breast, that’s very normal.
The overbust/underbust system is based on the difference between overbust measurement and full bust measurement. This usually works for people who have an average, proportioned build. If you are more athletic, this system will not work for you and the BCD system will be more accurate.