1) Android Icon Size

LDPI : 36×36 px

MDPI : 48×48 px

HDPI : 72×72 px

XHDPI : 96×96 px

XXHDPI : 144×144 px

XXXHDPI : 192×192 px

Market : 512×512 px

2) Android Splash Image Size

LDPI:

Portrait: 200×320 px

Landscape: 320×200 px

MDPI:

Portrait: 320×480 px

Landscape: 480×320 px

HDPI:

Portrait: 480×800 px

Landscape: 800×480 px

XHDPI:

Portrait: 720px1280 px

Landscape: 1280×720 px

XXHDPI:

Portrait: 960px1600 px

Landscape: 1600×960 px

XXXHDPI:

Portrait: 1280×1920 px

Landscape: 1920×1280 px

3) iOS Icon Size

iPhone : 57×57 px

iPad : 72×72 px

iPhone4 Retina : 114x114px

iPad3 Retina : 144×144 px

iTunes : 1024×1024 px

AppStore : 175×175 px

4) iOS Splash Image Size

Tablet (iPad)

Non-Retina (1x)

Portrait: 768×1024 px

Landscape: 1024x768px

Retina (2x)

Portrait: 1536×2048 px

Landscape: 2048×1536 px

Handheld (iPhone, iPod)

Non-Retina (1x)

Portrait: 320×480 px

Landscape: 480×320 px

Retina (2x)

Portrait: 640×960 px

Landscape: 960×640 px

iPhone 5 Retina (2x)

Portrait: 640×1136 px

Landscape: 1136×640 px

iPhone 6 (2x)

Portrait: 750×1334 px

Landscape: 1334×750 px

iPhone 6 Plus (3x)

Portrait: 1242×2208 px

Landscape: 2208×1242 px