Android DPI

http://developer.android.com/guide/practices/screens_support.html

To simplify the way that you design your user interfaces for multiple screens, Android divides the range of actual screen sizes and densities into:

• A set of four generalized sizes: small, normal, large, and xlarge

• A set of four generalized densities: ldpi (low), mdpi (medium), hdpi (high), and xhdpi (extra high)

Screen characteristic	Qualifier	Description
Size	small	Resources for small size screens.
	normal	Resources for normal size screens. (This is the baseline size.)
	large	Resources for large size screens.
	xlarge	Resources for extra large size screens.
Density	ldpi	Resources for low-density (ldpi) screens (~120dpi).
	mdpi	Resources for medium-density (mdpi) screens (~160dpi). (This is the baseline density.)
	hdpi	Resources for high-density (hdpi) screens (~240dpi).
	xhdpi	Resources for extra high-density (xhdpi) screens (~320dpi).
	nodpi	Resources for all densities. These are density-independent resources. The system does not scale resources tagged with this qualifier, regardless of the current screen's density.
	tvdpi	Resources for screens somewhere between mdpi and hdpi; approximately 213dpi. This is not considered a "primary" density group. It is mostly intended for televisions and most apps shouldn't need it—providing mdpi and hdpi resources is sufficient for most apps and the system will scale them as appropriate. If you find it necessary to provide tvdpi resources, you should size them at a factor of 1.33*mdpi. For example, a 100px x 100px image for mdpi screens should be 133px x 133px for tvdpi.
Orientation	land	Resources for screens in the landscape orientation (wide aspect ratio).
	port	Resources for screens in the portrait orientation (tall aspect ratio).
Aspect ratio	long	Resources for screens that have a significantly taller or wider aspect ratio (when in portrait or landscape orientation, respectively) than the baseline screen configuration.
	notlong	Resources for use screens that have an aspect ratio that is similar to the baseline screen configuration.

Table 3. Various screen configurations available from emulator skins in the Android SDK (indicated in bold) and other representative resolutions.

	Low density (120), ldpi	Medium density (160), mdpi	High density (240), hdpi	Extra high density (320), xhdpi
Smallscreen	QVGA (240x320)		480x640
Normalscreen	WQVGA400 (240x400) WQVGA432 (240x432)	HVGA (320x480)	WVGA800 (480x800) WVGA854 (480x854) 600x1024	640x960
Largescreen	WVGA800** (480x800) WVGA854** (480x854)	WVGA800* (480x800) WVGA854* (480x854) 600x1024
Extra Largescreen	1024x600	WXGA (1280x800)† 1024x768 1280x768	1536x1152 1920x1152 1920x1200	2048x1536 2560x1536 2560x1600