C:\Users\myname>systeminfo | FINDSTR /C:"Memory"
Total Physical Memory: 3.983 MB
Available Physical Memory: 1.148 MB
Virtual Memory: Max Size: 7.965 MB
Virtual Memory: Available: 4.571 MB
Virtual Memory: In Use: 3.394 MB
Try command systeminfo | FINDSTR /C:"Memory", it may kinda take long. Total Physical Memory: Actual RAM installed: 4GB. Virtual Memory: Max Size: Reserved space on the disk (paging/swap) for temporary fake RAM: 8GB. Virtual Memory: Available: Free cache memory, yet to be used for swap. Virtual Memory: In Use: Memory still written on disk, that are THAT required to be in RAM: 3.3GB.
If you want fast but untidy version: wmic MemoryChip get capacity, this will get you amount of RAM memory (official amount) in bytes. REMEMBER, this one isn't quite accurate, I have 4GB stick, so it will say 4294967296 bytes, but only 3.8GB is usable.