Beginning with Android 3.2 (API level 13), size groups (folders small, normal, large, xlarge) are deprecated in favor of a new technique for managing screen sizes based on the available screen width.
There are different resource configurations that you can specify based on the space available for your layout:
1)
Smallest Width - The fundamental size of a screen, as indicated by the shortest dimension of the available screen area.
Qualifier Value: sw'dp value'dp
Eg. res/sw600dp/layout.xml -> will be used for all screen sizes bigger or equal to 600dp. This does not take the device orientation into account.
2)
Available Screen Width - Specifies a minimum available width in dp units at which the resources should be used.
Qualifier Value: w'dp value'dp
Eg. res/w600dp/layout.xml -> will be used for all screens, which width is greater than or equal to 600dp.
3)
Available Screen Height - Specifies a minimum screen height in dp units at which the resources should be used.
Qualifier Value: h'dp value'dp
Eg. res/h600dp/layout.xml -> will be used for all screens, which height is greater than or equal to 600dp.
So at the end your folder structure might look like this:
res/layout/layout.xml -> for handsets (smaller than 600dp available width)
res/layout-sw600dp/layout.xml -> for 7” tablets (600dp wide and bigger)
res/layout-sw720dp/layout.xml -> for 10” tablets (720dp wide and bigger)
For more information please read the official documentation:
https://developer.android.com/guide/practices/screens_support.html#DeclaringTabletLayouts