Icon sizes for Android apps
Finding the correct icon sizes for Android apps can be a weird puzzle. Android's guidelines on iconography mention a lot of useful information but they don't break down the actual sizes your graphics designer requires.
Here are the sizes in pixels, calculated using Android's guidelines on iconography.
|Action Bar (optical square)||18x18||24x24||36x36||48x48||72x72||96x96|
|Action Bar (full size)||24x24||32x32||48x48||64x64||96x96||128x128|
|Small / Contextual Icons (optical square)||9x9||12x12||18x18||24x24||36x36||48x48|
|Small / Contextual Icons (full size)||12x12||16x16||24x24||32x32||48x48||64x64|
|Notification Icons (optical square)||16x16||22x22||33x33||44x44||66x66||88x88|
|Notification Icons (full size)||18x18||24x24||36x36||48x48||72x72||96x96|
And finally, the size for the launcher icons for Google Play must be 512x512 pixels.
The Android ecosystem is open to many device manufacturers who build devices on a vast variety of sizes and screen resolutions. That is why Android's way of calculating sizes for icons is based on relative rather than actual sizes.
As explained in the Iconography Guidelines, MDPI is the base for all calculations. LDPI is calculated as a 3/4 of MDPI, HDPI is 1.5 times larger than MDPI, XHDPI is 2 times MDPI, XXHDPI is 3 times MDPI and XXXHDPI is 4 times MDPI.
On some of the above dimensions you may notice a version for "optical square" and "full size". Icons must have the full size dimension but you should use the size for optical square and use the rest only when necessary.