Icon Sizes for Mobile Devices
Android
The standard icon size for an Android application on the home screen is 48x48 pixels. But the newer larger screens require larger icons. 48 pixels is now the “medium” resolution size. “High” resolution (hdpi) uses 72x72 pixels. “Extremely high” resolution (xhdpi) uses 96x96 pixels.
Icons for Android are square and do not have rounded corners.
iPhone and iPad
Icons for iOS are supposed to be made square. The software will add a rounded corner automatically. Also, they are not supposed to have a “shine,” because that also gets added by the system. In iOS 6, you can add the shine yourself, then set a flag that request the operating system not add shine. In iOS 7, this flag is gone, and submitting an icon that has shine is prohibited.
The icon for an iPhone application must be 57x57 pixels. For a retina screen, you must double those dimensions to 114x114 pixels. The icon for an iPad application must be 72x72 pixels. For a retina screen, you must double those dimensions to 144x144 pixels.
The rounded corner radius applied to your icon will be about 10/57 or 17.54%. You can supply a square icon and the rounded corner will be applied automatcially. (The rounded icons below are actually square icons with the rounded corner applied in CSS.)
The icon sizes changed in iOS 7. iPhone icons are 120x120 pixels. iPad icons are 76x76 pixels, or 152x152 pixels for retina displays.
The rounded corners appled in iOS 7 have a slightly different shape. You still don’t really need to worry about this a lot, because it will be applied to your square icon automatically.
Windows Phone
The icon for Windows Phone must be 62x62 pixels.