Microsoft put a large amount of thought into screen resolution, which varies as much as screen size does. One of the most important considerations was in defining a minimum resolution of 1024 x 768 pixels required for the display of Metro apps. Washington pointed out that this would support 98.8 percent of Windows 7 installations, and that the minimum would make apps richer as well as prevent developers from having to test apps at resolutions below that. Similarly, to use the Snap feature, which allows multiple apps to share the screen, a minimum resolution of 1366 x 768 is required, which allows a 1024 pixel-wide app, as well as a 320 pixel-wide sidebar.

Relating to maximum resolution, Washington said, "You can run Metro style apps on a screen as big as 30 inches with a resolution of 2560 x 1600." Though it's unclear if this means Metro will not run on a higher resolution, it's more likely that this is an example of a large resolution that Metro supports.

Screen density as a measurement hasn't been used much until recently. Screen or pixel density refers to the number of pixels in a physical area, also known as dots per inch (DPI). Apple made the concept popular when it first introduced the Retina display in its iPhone 4, and about the 9.7-inch, 2048 x 1536 resolution, 264 DPI version in the new iPad. Since the new iPad has twice as many pixels in each dimension, screen elements in iOS are scaled up 200 percent so they don't look tiny, and remain touch friendly.

Windows 8 will support a much wider range of devices than iOS, so Microsoft is targeting three scaling factors that apps will automatically adjust to so they are appropriately sized on any screen: