The output of the free command that I fired on my linux host is as belows:

              total        used        free      shared  buff/cache   available
Mem:      263846320    47746620     3290072     1140808   212809628   214382420
Swap:             0           0           0

I am not able to figure out what this available part is specifying. The free memory is very less shown i.e around 1.24% even though the total memory is way high and used memory is around 18.09% only.

free -h
              total        used        free      shared  buff/cache   available
Mem:           251G         45G        3.1G        1.1G        202G        204G
Swap:            0B          0B          0B

Does it mean I wont be able to start more applications as free memory is very less. The used memory is 18% only. So shouldn't free memory be 72% and not 1.24% as the command is showing above.

I am confused. Can anyone help?


In the output of free,

  • Free memory is the amount of memory which is currently not used for anything. This number should be small, because memory which is not used is simply wasted.

  • Available memory is the amount of memory which is available for allocation to a new process or to existing processes.

The example given in the question shows a healthy system.

  • 4
    How the available and buff/cache columns are different from each other. – srinivas Jan 2 '19 at 13:15
  • @srinivas, available does include free column + a part of buff/cache which can be reused for current needs immediately – ALZ Nov 8 '19 at 10:36
  • 4
    this answer convoluted things for me even more – markroxor Aug 13 '20 at 8:48
  • Yeah I also don't get it... How is the free memory different from available? Apparently free is a subset of available, but.... what? How? Why? More questions than answers. – Simon Forsberg Aug 21 '20 at 22:15
  • 8
    Ok, I just read linuxatemyram.com which explains a lot. – Simon Forsberg Aug 21 '20 at 22:24

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