Multi-Resolution Windows .ICO & Website Favicon Generation
The .ico file format is the foundational standard for Windows desktop icons, software applications, taskbar shortcuts, and website browser tab favicons. Unlike common raster formats like PNG and JPG that only store a single image, an ICO container is specifically designed to store multiple resolutions and color depths inside a single binary file.
When you provide a multi-size .ico file, Windows Explorer and modern web browsers automatically sample the optimal resolution according to the screen's DPI scaling and display mode, eliminating blurry or pixelated icons on 4K and Retina monitors.
Standard ICO Resolutions & Use Cases
- 16 × 16: Browser tab favicons, address bars, and small taskbar shortcuts.
- 32 × 32: Standard Windows desktop icons and bookmarks bars.
- 48 × 48: Windows Explorer medium icons and legacy start menu entries.
- 64 × 64: High-DPI Windows display scaling and notification areas.
- 128 × 128: Windows Explorer large icon tiles.
- 256 × 256: Windows 10/11 extra large icon tiles and modern application packaging.
Client-Side 32-Bit RGBA Transparency Preservation
Our binary encoder maintains full 32-bit alpha channel transparency from source PNG and WebP files. No white halos or jagged edges are introduced. The tool runs completely inside your browser using the HTML5 Canvas API and DataView binary streams, guaranteeing total privacy and zero server latency.
Frequently Asked Questions
How does the Image to ICO converter pack multiple resolutions into one file?
The ICO format uses a binary directory container (ICONDIR) containing headers for each individual resolution (16x16, 32x32, 48x48, 64x64, 128x128, 256x256). Our client-side binary packer bundles these resolutions together so Windows and web browsers automatically select the sharpest size for any screen density.
Can I convert transparent PNG images to ICO without losing transparency?
Yes. 32-bit RGBA alpha channel transparency is completely preserved. The transparent pixels in your PNG or WebP image remain transparent in the resulting .ico file.
What image formats can I convert to ICO?
You can convert PNG, JPG, JPEG, and WebP images up to 25MB.
Are my images uploaded to any server?
No. All resizing, canvas processing, and binary byte packing execute locally inside your web browser. Your images never leave your computer.
What are the standard ICO sizes for websites and Windows apps?
16x16 and 32x32 are standard for browser tab favicons and bookmarks. 48x48 and 64x64 are used for Windows taskbar and desktop shortcuts, while 128x128 and 256x256 provide crisp high-resolution icons for Windows Explorer and high-DPI displays.