How do I display available/used device memory in my game?

Hi guys,

as the title says, I am looking to figure out how to display how much free memory my mobile device has left.

I am currently displaying the following:

fps & " FPS, " & round(cpuutilisation * 100) & "% CPU (" & renderer & "), " & ImageMemoryUsage & "MB"

This is working fine but doesn't give me any data on how much memory the device uses in total.

Any help would be appreciated.