Physical Memory Utilization Calculation:
Note: For version 16800 and above , the Skip option will be under Settings -> Performance Polling -> Servers -> Linux monitor type.
Formula:
(i) If Skip buffer and cache from monitoring (Applicable only for linux) option under Settings -> Performance Polling -> Servers Tab is not enabled. [By default, this option is not enabled]

Memory Utilization (%) = 100 -(((MemFree + Buffers + Cached)*100)/maxValue)
Memory Utilization (MB) = maxValue-(MemFree + Buffers + Cached)
(ii) If Skip buffer and cache from monitoring (Applicable only for linux) option under Settings -> Performance Polling -> Servers Tab is enabled.

Memory Utilization (%) = 100 - ((MemFree *100)/maxValue)
Memory Utilization (MB) = maxValue - MemFree
In Telnet/SSH mode:

testuser@testmachine:~$ free -b
total used free shared buff/cache available
Mem: 12361719808 8122318848 274104320 370192384 3965296640 3541422080
Swap: 32212250624 4870012928 27342237696

MemFree corresponds to Mem:free
Buffers + Cached corresponds to Mem:buff/cache
maxValue corresponds to Mem:total
(i) If Skip buffer and cache from monitoring (Applicable only for linux) option under Settings -> Performance Polling -> Servers Tab is not enabled.

Memory Utilization (%) = 100 -(((MemFree + Buffers + Cached)*100)/maxValue)
= 100 -(((274104320 + 3965296640)*100)/12361719808)
= 65.705411336 = 65 %

Memory Utilization (MB) = maxValue-(MemFree + Buffers + Cached)
= 12361719808 - (274104320+3965296640)
= 8122318848/(1024*1024)
= 7746 MB
(ii) If Skip buffer and cache from monitoring (Applicable only for linux) option under Settings -> Performance Polling -> Servers Tab is enabled.

Memory Utilization (%) = 100 - ((MemFree *100)/maxValue)
= 100 - ((274104320 *100)/12361719808)
= 97.782636039 = 97%

Memory Utilization (MB) = maxValue - MemFree
= 12361719808 - 274104320
= 12087615488/(1024*1024)
= 11527 MB
Swap Memory Utilization:
Used % = ( used_swap / total_swap ) *100
= ( 4870012928/ 32212250624) * 100
= 15 %
Total Memory Utilization
total_used = used_mem + used_swap
= 6817 + 0
= 6817
Total used % = ( ( total_used ) / ( total_mem + total_swap ) ) * 100);
= ( ( 6817) / ( 15726 + 30719 ) ) * 100
= 14 %