Physical memory or RAM usage in Percentage

Hello roopesh_shetty 

Mostly It looks correct to me, what time are you scoping the query on (default is 24hrs), are the numbers higher or lower than expected?

TotalSizeGB is wrong - I mentioned that, I'll let you find the correct counter(s) or method for that. 

The query is a sample of the technique not the finished solution - so it might need some adjustment - sorry I didn't make that clearer in my response (it comes from a similar solution with disk space, where averages work fine, and the data fluctuates less).  

The query uses averages where as if you look at Task Manager for example you get the actuals/avg over a small time window.  The query is also time-wise behind the real machines (ingestion time delays etc...).  In my case I used an RDS server and a DC that I know are pretty stable.   FreeGb and PctFree seem ok, but I've not looked at them for very long.  If your servers are busy and the values are fluctuating and you are measuring over 24hrs for instance then the averages maybe very different, perhaps scope to the last hour or even use the between operator to scope accurately.  You may need to change the query from avg to max or whatever aggregation you require. 

Thank you