Good to have when editing icons for Android:

• drawable-ldpi (120 dpi, Low density screen) - 36px x 36px
• drawable-mdpi (160 dpi, Medium density screen) - 48px x 48px
• drawable-hdpi (240 dpi, High density screen) - 72px x 72px
• drawable-xhdpi (320 dpi, Extra-high density screen) - 96px x 96px