Android screen size and densities.

Table 1. Screen sizes and densities of emulator skins included in the Android SDK and other representative resolutions.

	Low density (120), ldpi	Medium density (160), mdpi	High density (240), hdpi	Extra high density (320), xhdpi
Small screen	QVGA (240x320)		480x640
Normal screen	WQVGA400 (240x400) WQVGA432 (240x432)	HVGA (320x480)	WVGA800 (480x800) WVGA854 (480x854) 600x1024	640x960
Large screen	WVGA800** (480x800) WVGA854** (480x854)	WVGA800* (480x800) WVGA854* (480x854) 600x1024
Extra Large screen	600x1024	768x1024 WXGA (768x1280) 800x1280	1152x1536 1152x1920 1200x1920	1536x2048 1536x2560 1600x2560

* To emulate this configuration, specify a custom density of 160 when creating an AVD that uses a WVGA800 or WVGA854 skin.

** To emulate this configuration, specify a custom density of 120 when creating an AVD that uses a WVGA800 or WVGA854 skin.

***Density-independent pixel(dip):dip是一种虚拟的像素单位,专门用来给程序定义UI用,Android高度推荐使用这个,可以为不同的dip设置不同的资源进行自动切换
pixels = dips * (density / 160)即dip相当于屏幕density=160时的一个像素点，density=160时是一个点显示一个像素，而density=240时是3个点显示两个像素，图像看起来大一些，真实像素只有1280*2/3px,800*2/3px。