GlobalMemoryStatusEx function (sysinfoapi.h)

Retrieves information about the system's current usage of both physical and virtual memory.


BOOL GlobalMemoryStatusEx(
  [in, out] LPMEMORYSTATUSEX lpBuffer


[in, out] lpBuffer

A pointer to a MEMORYSTATUSEX structure that receives information about current memory availability.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.


You can use the GlobalMemoryStatusEx function to determine how much memory your application can allocate without severely impacting other applications.

The information returned by the GlobalMemoryStatusEx function is volatile. There is no guarantee that two sequential calls to this function will return the same information.

The ullAvailPhys member of the MEMORYSTATUSEX structure at lpBuffer includes memory for all NUMA nodes.


The following code shows a simple use of the GlobalMemoryStatusEx function.

//  Sample output:
//  There is       51 percent of memory in use.
//  There are 2029968 total KB of physical memory.
//  There are  987388 free  KB of physical memory.
//  There are 3884620 total KB of paging file.
//  There are 2799776 free  KB of paging file.
//  There are 2097024 total KB of virtual memory.
//  There are 2084876 free  KB of virtual memory.
//  There are       0 free  KB of extended memory.

#include <windows.h>
#include <stdio.h>
#include <tchar.h>

// Use to convert bytes to KB
#define DIV 1024

// Specify the width of the field in which to print the numbers. 
// The asterisk in the format specifier "%*I64d" takes an integer 
// argument and uses it to pad and right justify the number.
#define WIDTH 7

void _tmain()

  statex.dwLength = sizeof (statex);

  GlobalMemoryStatusEx (&statex);

  _tprintf (TEXT("There is  %*ld percent of memory in use.\n"),
            WIDTH, statex.dwMemoryLoad);
  _tprintf (TEXT("There are %*I64d total KB of physical memory.\n"),
            WIDTH, statex.ullTotalPhys/DIV);
  _tprintf (TEXT("There are %*I64d free  KB of physical memory.\n"),
            WIDTH, statex.ullAvailPhys/DIV);
  _tprintf (TEXT("There are %*I64d total KB of paging file.\n"),
            WIDTH, statex.ullTotalPageFile/DIV);
  _tprintf (TEXT("There are %*I64d free  KB of paging file.\n"),
            WIDTH, statex.ullAvailPageFile/DIV);
  _tprintf (TEXT("There are %*I64d total KB of virtual memory.\n"),
            WIDTH, statex.ullTotalVirtual/DIV);
  _tprintf (TEXT("There are %*I64d free  KB of virtual memory.\n"),
            WIDTH, statex.ullAvailVirtual/DIV);

  // Show the amount of extended memory available.

  _tprintf (TEXT("There are %*I64d free  KB of extended memory.\n"),
            WIDTH, statex.ullAvailExtendedVirtual/DIV);


Requirement Value
Minimum supported client Windows XP [desktop apps | UWP apps]
Minimum supported server Windows Server 2003 [desktop apps | UWP apps]
Target Platform Windows
Header sysinfoapi.h (include Windows.h)
Library Kernel32.lib
DLL Kernel32.dll

See also


Memory Management Functions

Memory Performance Information

Virtual Address Space and Physical Storage