Images in mobile apps must balance visual quality with file size and performance. Oversized or poorly formatted images cause slow load times, high memory usage, and app crashes — all of which drive negative reviews and user abandonment. At imgresizr.com, you can optimise images for iOS and Android apps at the correct resolution, format, and compression, completely free.
Mobile App Image Optimisation Standards
| Platform | Resolution | Format | Max Size |
|---|---|---|---|
| iOS (iPhone) | @1x, @2x, @3x | PNG or WebP | 500KB per image |
| Android (MDPI-XXXHDPI) | mdpi to xxxhdpi | WebP preferred | 500KB per image |
How to Optimise App Images at imgresizr.com
Upload your image to imgresizr.com. For iOS, you need three sizes: @1x (base), @2x (retina), and @3x (super retina). If your base image needs to be 200×200px, create versions at 200px, 400px, and 600px. Use the Resize tool to generate each size. Convert to WebP using the Convert tool — WebP files are typically 25–35% smaller than equivalent PNG or JPG while maintaining visual quality. For background images and hero images, resize to the maximum screen dimension you support (typically 1242×2688px for the largest iPhone). For icons and small UI elements, use PNG with transparency. Compress all images to under 500KB using the Compress tool. The smaller your app's total image assets, the faster it downloads and launches.
Mobile App Image Best Practices
- Always provide multiple density versions — a single @1x image looks blurry on retina displays
- Use WebP for all non-transparent images — Apple and Android both support it natively since 2019
- Lazy-load images that appear below the fold — do not load what is not visible
- Cache images locally where possible — avoid network requests for static assets
- Test on a real device, not just a simulator — performance characteristics differ significantly
Optimise images for iOS and Android apps at the correct resolution and format, free at imgresizr.com.