How to determine whether a computer is running a 32-bit version or 64-bit version of the Windows operating system

This article describes how to determine whether a computer is running a 32-bit version or 64-bit of the Windows operating system. Generally, a computer's bit count indicates how much data it can process, the speed with which it can process the data, and the memory capacity. In order to optimize the computer's performance, the bit count of the operating system that is installed on the computer should match the bit count of the computer itself.

Determine the operating system bit count
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Locate the operating system that is running on your computer in this section, and then follow the steps to determine the bit count of your operating system.
Windows Vista
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If you have Windows Vista, there are two methods to determine whether you are running a 32-bit or a 64-bit version. If one does not work, try the other.
Method 1: View System window in Control Panel
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Click Start
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, type system in the Start Search box, and then click system in the Programs list.
The operating system is displayed as follows:
For a 64-bit version operating system: 64-bit Operating System appears for the System type under System.
For a 32-bit version operating system: 32-bit Operating System appears for the System type under System.
Method 2: View System Information window
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Click Start
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, type system in the Start Search box, and then click System Information in the Programs list.
When System Summary is selected in the navigation pane, the operating system is displayed as follows:
For a 64-bit version operating system: x64-based PC appears for the System type under Item.
For a 32-bit version operating system: x86-based PC appears for the System type under Item.If you cannot determine the operating system bit count with these methods, go to the "Next Steps" section.
Windows XP
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If you have Windows XP, there are two methods to determine whether you are running a 32-bit or a 64-bit version. If one does not work, try the other.
Method 1: View System Properties in Control Panel
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Click Start, and then click Run.
Type sysdm.cpl, and then click OK.
Click the General tab. The operating system is displayed as follows:
For a 64-bit version operating system: Windows XP Professional x64 Edition Version <> appears under System.
For a 32-bit version operating system: Windows XP Professional Version appears under System. Note is a placeholder for a year.
Method 2: View System Information window
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Click Start, and then click Run.
Type winmsd.exe, and then click OK.
When System Summary is selected in the navigation pane, locate Processor under Item in the details pane. Note the value.
If the value that corresponds to Processor starts with x86, the computer is running a 32-bit version of Windows.
If the value that corresponds to Processor starts with ia64 or AMD64, the computer is running a 64-bit version of Windows.If you cannot determine the operating system bit count with these methods, go to the "Next Steps" section.
Windows Server 2003
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If you have Windows Server 2003, there are two methods to determine whether you are running a 32-bit or a 64-bit version. If one does not work, try the other.
Method 1: View System Properties in Control Panel
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Click Start, and then click Run.
Type sysdm.cpl, and then click OK.
Click the General tab. The operating system is displayed as follows:
For a 64-bit version operating system: Windows Server 2003 Enterprise x64 Edition appears under System.
For a 32-bit version operating system: Windows Server 2003 Enterprise Edition appears under System.
Method 2: View System Information window
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Click Start, and then click Run
Type winmsd.exe, and then click OK.
When System Summary is selected in the navigation pane, locate Processor under Item in the details pane. Note the value.
If the value that corresponds to Processor starts with x86, the computer is running a 32-bit version of Windows.
If the value that corresponds to Processor starts with EM64T or ia64, the computer is running a 64-bit version of Windows.If you cannot determine the operating system bit count by using these methods, go to the "Next Steps" section.Notes
To find the computer’s bit count, see the documentation that was included with the computer, or contact the hardware manufacturer.
Intel Itanium-based computers can run only 64-bit versions of Windows. Intel Itanium-based computers cannot run 32-bit versions of Windows. Currently, 64-bit versions of Windows run only on Itanium-based computers and on AMD64-based computers.