What is the Android Icon Size for an App?
For Android launcher icons you will need 6 sizes of PNG or JPG files. In pixels these are 48×48, 72×72, 96×96, 144×144, 192×192 and 512×512. The first five are for the App and the last one for when the App is deployed to the Google Play store. These are the final size of the icons and you must allow for a small margin, hence the area the icon is drawn in will be a bit smaller. For low density screens Android halves the 72×72 icon, but it is possible to include a 36×36 icon in the App for completeness, making 7 icons in total. An Android icon size table in this article summarizes all the relevant information.
Android Screen Densities
The number of dots (pixels) per inch that an Android device’s screen holds determines how sharp the image on the screen looks. The more Dots Per Inch (DPI) the sharper the image. Android groups screen densities into several classes, medium, high, extra high, extra extra high and extra extra extra high! These are referred to as MDPI, HDPI, XHDPI, XXHDPI and XXXHDPI. There is also a low density class, LDPI, however not many new devices have a low density screen and thus LDPI is no longer important. MDPI is around 160 DPI, HDPI around 240 DPI, XHDPI around 320 DPI, XXHDPI around 480 DPI and XXXHDPI around 640 DPI. (LDPI is around 120 DPI). It is the screen density that determines the Android icon size used.