What is buffer account? & and how to count?

[Skiz]

Buffer IS Upload - Download
Example : U Have Downloaded 2 gb , and uploaded 3 gb , the buffer is :: 3-2=1
the buffer here is 1 gb

If minimum ratio of site is 0.6
and i downloaded 100GB and uploaded 100GB
what about that 40GB

That has no bearing. A buffer is how much you've uploaded over your download, period.