Comparing Cached Free Memory with Top, Meminfo, and Free
 

with:

cat /proc/meminfo && free -k && top -n1 | head

I am trying to compare the cached ram that is free for use. For these amount info in:

top: ###### cached
meminfo: ##### inactive
free: ##### free for buffers/cached

They are not the same or that close. Why is this?

Because they are different metrics.
"Inactive" is a subset of "cached+buffers" - the numbers in the second line of "free" (to which I presume you are referring) are a calculated indication of "total" free memory on the system.

Moved: This thread is more suitable in Linux - Software and has been moved accordingly to help your thread/question get the exposure it deserves.