How much RAM does blender need per poly?


Is there any reliable place where I can find information on how much memory does Blender need per face / vertex? I’m trying to sculpt really high poly model (without luck really…) and am wondering what are actual blender limits depending on installed hardware. I know that I don’t have enough memory because when I look at the memory monitor it looks like blender is recycling memory with every action I make (causing it to freeze). But my question is, how much do I actually need?

Going by simple calculations like 24 bytes / vertex + possibly around another 100 (24 for normal, 8 for vertex pointer x3-4, and small reserve for things I don’t know about) per face I get something around 22.8MB + around 100MB per 1mln polygon… and I know that this is not true, because that would mean that 100mln poly would need only around 12,28GB of RAM and I know for a fact, that I can’t get anywhere close to that number.

Is there any way that would show me / calculate that “If you want a model with X poly, then you need Y RAM for sculpting” ?