Experience Index

The Windows System Assessment Tool (WinSAT) is a module of Microsoft Windows Vista, Windows 7, and Windows 8 that is available in the Control Panel under Performance Information and Tools (except in Windows 8.1). It measures various performance characteristics and capabilities of the hardware it is running on and reports them as a Windows Experience Index (WEI) score. The WEI includes five subscores: processor, memory, 2D graphics, 3D graphics, and disk; the basescore is equal to the lowest of the subscores. WinSAT reports WEI scores on a scale from 1.0 to 5.9 (for Windows Vista/YourStudent), 7.9 (for Windows 7/PAP-West/Transmetro), or 9.9 (for Windows 8/Skyfall).

The WEI enables users to match their computer hardware performance with the performance requirements of software. For example, the Aero graphical user interface will not automatically be enabled unless the system has a WEI score of 3 or higher.

The WEI can also be used to show which part of a system would be expected to provide the greatest increase in performance when upgraded. For example a computer with the lowest subscore being its memory, would benefit more from a RAM upgrade than adding a faster hard drive (or any other component).

Microsoft intends that software publishers list WEI scores to specify hardware requirements instead of specific technical parameters (such as "256 MB of RAM or more"). Microsoft also intends that hardware manufacturers publish the WEI scores of their computers. However, very few software or hardware vendors have done so to date.

The WEI is also available to applications through an API, so they can configure themselves as a function of hardware performance, taking advantage of its capabilities without becoming unacceptably slow.

The Windows Experience Index score is not displayed in Windows 8.1 although the command line winsat tool still exists and operates correctly.