Something has plagued my mind for some time now, /e/

Many of these japanese series, be they video game, anime, manga, or what have you, seem to only offer the Bust-Waist-Hips three-size measurements to describe the attributes of the female characters, but it's a rare occasion that they actually list the cup size.

Is there any sort of formula out there that you can use to give estimated cup sizes based on three-size measurements? I'm not looking for perfect accuracy, but something that can give reasonable ballparking.

I figure if there were any board to ask this sort of question to, /e/ would be it.