Memory Limits in Windows OS

Memory and Address Space Limits

The following table specifies the limits on memory and address space for supported releases of Windows.

Memory type	Limit in 32-bit Windows	Limit in 64-bit Windows
User-mode virtual address space for each 32-bit process	2 GB Up to 3 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE and 4GT	2 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE cleared (default) 4 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE set
User-mode virtual address space for each 64-bit process	Not applicable	With IMAGE_FILE_LARGE_ADDRESS_AWARE set (default): x64:  8 TB Intel IPF:  7 TB 2 GB with IMAGE_FILE_LARGE_ADDRESS_AWARE cleared
Kernel-mode virtual address space	2 GB From 1 GB to a maximum of 2 GB with 4GT	8 TB
Paged pool	Limited by available kernel-mode virtual address space or the PagedPoolLimit registry key value. Windows Vista:  Limited only by kernel mode virtual address space. Starting with Windows Vista with Service Pack 1 (SP1), the paged pool can also be limited by the PagedPoolLimit registry key value. Windows Home Server and Windows Server 2003:  530 MB Windows XP:  490 MB Windows 2000:  350 MB	128 GB Windows Server 2003 and Windows XP:  Up to 128 GB depending on configuration and RAM. Windows 2000:  Not applicable
Nonpaged pool	Limited by available kernel-mode virtual address space, the NonPagedPoolLimit registry key value, or physical memory. Windows Vista:  Limited only by kernel mode virtual address space and physical memory. Starting with Windows Vista with SP1, the nonpaged pool can also be limited by the NonPagedPoolLimit registry key value. Windows Home Server, Windows Server 2003, and Windows XP/2000:  256 MB, or 128 MB with 4GT.	75% of RAM up to a maximum of 128 GB Windows Vista:  40% of RAM up to a maximum of 128 GB. Windows Server 2003 and Windows XP:  Up to 128 GB depending on configuration and RAM. Windows 2000:  Not applicable
System cache virtual address space (physical size limited only by physical memory)	Limited by available kernel-mode virtual address space or the SystemCacheLimit registry key value. Windows Vista:  Limited only by kernel mode virtual address space. Starting with Windows Vista with SP1, system cache virtual address space can also be limited by the SystemCacheLimit registry key value. Windows Home Server, Windows Server 2003, and Windows XP/2000:  860 MB with LargeSystemCache registry key set and without 4GT; up to 448 MB with 4GT.	Always 1 TB regardless of physical RAM Windows Server 2003 and Windows XP:  Up to 1 TB depending on configuration and RAM. Windows 2000:  Not applicable

 

Physical Memory Limits: Windows 7

The following table specifies the limits on physical memory for Windows 7.

Version	Limit in 32-bit Windows	Limit in 64-bit Windows
Windows 7 Ultimate	4 GB	192 GB
Windows 7 Enterprise	4 GB	192 GB
Windows 7 Professional	4 GB	192 GB
Windows 7 Home Premium	4 GB	16 GB
Windows 7 Home Basic	4 GB	8 GB
Windows 7 Starter	2 GB	2 GB

 

Physical Memory Limits: Windows Server 2008 R2

The following table specifies the limits on physical memory for Windows Server 2008 R2. Windows Server 2008 R2 is available only in 64-bit editions.

Version	Limit in 64-bit Windows
Windows Server 2008 R2 Datacenter	2 TB
Windows Server 2008 R2 Enterprise	2 TB
Windows Server 2008 R2 for Itanium-Based Systems	2 TB
Windows Server 2008 R2 Foundation	8 GB
Windows Server 2008 R2 Standard	32 GB
Windows HPC Server 2008 R2	128 GB
Windows Web Server 2008 R2	32 GB

 

Physical Memory Limits: Windows Server 2008

The following table specifies the limits on physical memory for Windows Server 2008. Limits greater than 4 GB for 32-bit Windows assume that PAE is enabled.

Version	Limit in 32-bit Windows	Limit in 64-bit Windows
Windows Server 2008 Datacenter	64 GB	2 TB
Windows Server 2008 Enterprise	64 GB	2 TB
Windows Server 2008 HPC Edition	Not applicable	128 GB
Windows Server 2008 Standard	4 GB	32 GB
Windows Server 2008 for Itanium-Based Systems	Not applicable	2 TB
Windows Small Business Server 2008	4 GB	32 GB
Windows Web Server 2008	4 GB	32 GB

 

Physical Memory Limits: Windows Vista

The following table specifies the limits on physical memory for Windows Vista.

Version	Limit in 32-bit Windows	Limit in 64-bit Windows
Windows Vista Ultimate	4 GB	128 GB
Windows Vista Enterprise	4 GB	128 GB
Windows Vista Business	4 GB	128 GB
Windows Vista Home Premium	4 GB	16 GB
Windows Vista Home Basic	4 GB	8 GB
Windows Vista Starter	1 GB	Not applicable

 

Physical Memory Limits: Windows Home Server

Windows Home Server is available only in a 32-bit edition. The physical memory limit is 4 GB.

Physical Memory Limits: Windows Server 2003

The following table specifies the limits on physical memory for Windows Server 2003. Limits over 4 GB for 32-bit Windows assume that PAE is enabled.

Version	Limit in 32-bit Windows	Limit in 64-bit Windows
Windows Server 2003 with Service Pack 2 (SP2), Datacenter Edition	128 GB 64 GB with 4GT	2 TB
Windows Server 2003 with Service Pack 2 (SP2), Enterprise Edition	64 GB	2 TB
Windows Storage Server 2003, Enterprise Edition	8 GB	Not applicable
Windows Storage Server 2003	4 GB	Not applicable
Windows Server 2003 R2 Datacenter Edition Windows Server 2003 with Service Pack 1 (SP1), Datacenter Edition	128 GB 16 GB with 4GT	1 TB
Windows Server 2003 R2 Enterprise Edition Windows Server 2003 with Service Pack 1 (SP1), Enterprise Edition	64 GB 16 GB with 4GT	1 TB
Windows Server 2003 R2 Standard Edition Windows Server 2003, Standard Edition SP1 Windows Server 2003, Standard Edition SP2	4 GB	32 GB
Windows Server 2003, Datacenter Edition	128 GB 16 GB with 4GT	512 GB
Windows Server 2003, Enterprise Edition	32 GB 16 GB with 4GT	64 GB
Windows Server 2003, Standard Edition	4 GB	16 GB
Windows Server 2003, Web Edition	2 GB	Not applicable
Windows Small Business Server 2003	4 GB	Not applicable
Windows Compute Cluster Server 2003	Not applicable	32 GB

 

Physical Memory Limits: Windows XP

The following table specifies the limits on physical memory for Windows XP.

Version	Limit in 32-bit Windows	Limit in 64-bit Windows
Windows XP	4 GB	128 GB
Windows XP Starter Edition	512 MB	Not applicable

 

Physical Memory Limits: Windows 2000

The following table specifies the limits on physical memory for Windows 2000.

Version	Limit in 32-bit Windows
Windows 2000 Professional	4 GB
Windows 2000 Server	4 GB
Windows 2000 Advanced Server	8 GB
Windows 2000 Datacenter Server	32 GB