Pixel Densities

Android icons require five separate sizes for different screen pixel densities. Icons for lower resolution are created automatically from the baseline.

尺寸	dpi	倍数
mdpi (Baseline)	160 dpi	1×
hdpi	240 dpi	1.5×
xhdpi	320 dpi	2×
xxhdpi	490 dpi	3×
xxxhdpi	640 dpi	4×

Launcher icons

Sizes (px)	Format and naming
48 × 48 (mdpi)	.png
72 × 72 (hdpi)
96 × 96 (xhdpi)
144 × 144 (xxhdpi)
192 × 192 (xxxhdpi)
512 × 512 (Google Play store)

NOTO: Three-dimensional, front view, with a slight perspective as if viewed from above, so that users perceive some depth.

Action bar, Dialog & Tab icons

Sizes (px)	Format and naming
24 × 24 area in 32 × 32 (mdpi)	.png
36 × 36 area in 48 × 48 (hdpi)
48 × 48 area in 64 × 64 (xhdpi)
72 × 72 area in 96 × 96 (xxhdpi)
96 × 96 area in 128 × 128 (xxxhdpi)

NOTE: These icons are used in the action bar menu. The first number is the size of the icon area, and the second is file size.

Small Contextual Icons

Sizes (px)	Format and naming
16 × 16 (mdpi)	.png
24 × 24 (hdpi)
32 × 32 (xhdpi)
48 × 48 (xxhdpi)
64 × 64 (xxxhdpi)

Notes: Small icons are used to surface actions and/or provide status for specific items. For example, in the Gmail app, each message has a star icon that marks the message as important.

Notification icons

Sizes (px)	Format and naming
22 × 22 area in 24 × 24 (mdpi)	.png
33 × 33 area in 36 × 36 (hdpi)
44 × 44 area in 48 × 48 (xhdpi)
66 × 66 area in 72 × 72 (xxhdpi)
88 × 88 area in 96 × 96 (xxxhdpi)

Notes: These are used to represent application notifications in the status bar. They should be flat (no gradients), white and face-on perspective

See also http://iconhandbook.co.uk/reference/chart/android/