Usage share metrics from California analytics company Net Applications can be combined with Microsoft's claim that 1.4 billion Windows PCs run Windows worldwide, a number reiterated Tuesday by Julie Larson-Green, who heads Windows development. Caveats apply: Net Applications' data is based on accessing the Internet, so it cannot account for hardware that doesn't go online, and the firm massages its raw data, weighting users by their country of origin, to come up with what it believes is a more accurate representation of operating system usage.
For April, Windows 8's average usage share was 4.2% of all Windows PCs, according to Net Applications' data. That number included what Net Applications labeled as "touch" for Windows 8 and Windows RT, those tablets and touch-enabled notebooks that browse the Web from the "Modern" user interface (UI) rather than the mouse-and-keyboard UI of the traditional desktop.
Four-point-two percent of 1.4 billion equals approximately 58.6 million, the number of devices using Windows 8 last month.
Those same calculations also illustrate the huge chore Microsoft and its customers, predominantly enterprises, have in ditching the 12-year-old Windows XP before April 2014's support retirement deadline. Using the same math, XP powers about 584.4 million machines, or well over half a billion PCs.
Windows 7? 682.2 million. Vista? 72.5 million, still more than Windows 8. What about Windows NT, the operating system first released in 1993, or two decades ago? 1.7 million PCs.