What is an Android Mipmap?

When developing for Android, you'll notice two main folders for images in your res/ directory: drawable and mipmap. While they seem similar, placing your app's launcher icon in the wrong folder can result in blurry graphics on users' home screens.

Mipmap vs Drawable

Drawable folders (drawable-hdpi, drawable-xhdpi, etc.) are used for all UI assets inside your app. If a user installs your app on an xxhdpi device, the Android system strips out all the other density folders from the final APK to save space.

Mipmap folders (mipmap-hdpi, mipmap-xhdpi, etc.) are explicitly reserved for launcher icons.Android never strips mipmap resources from the APK.

Why does Android keep all Mipmaps?

Home screen launchers on Android often display icons larger than their native device density requires. For example, a launcher on an xhdpi device might choose to upscale icons by 20% to make them look larger and friendlier.

If your icon was in a drawable-xhdpi folder, the launcher would be forced to take the 96x96 image and stretch it, making it blurry. However, because your icons are in mipmap folders, the launcher can safely reach into the mipmap-xxhdpi folder, pull out the crisp 144x144 image, and scale it down, resulting in a perfect, sharp icon.