How to calculate memory usage as Task Manager does?

Question

Ok so I am using WMI (.net/C#) to constantly collect data about a specific process that is running on the machine. I get the data through Win32_PerfFormattedData_PerfProc_Proces

Answer 1

Win32_PerfFormattedData_PerfProc_Process is the correct class. The property it pulls from is WorkingSetPrivate. No formula/calculation needed.