How offline PNG to ICO conversion works
This tool uses your browser's Canvas API — no external libraries, no WebAssembly, no server. When you drop an image, the browser decodes it natively, draws it to a canvas, and exports it in an ICO-compatible format. At no point does the file leave your device.
What is an ICO file?
ICO is the Microsoft icon file format, most commonly used for favicons — the small icon that appears in browser tabs, bookmarks, and on the address bar next to your website's URL. Despite being decades old, ICO remains the standard that all browsers check for favicons.
When a browser loads your site, it automatically looks for /favicon.ico at the root of your domain. If found, it displays that icon in the tab. Our converter creates files you can place at that exact path.
Recommended favicon sizes
| Size | Use case |
|---|---|
| 16 × 16 | Browser tab, address bar icon |
| 32 × 32 | Bookmarks bar, taskbar shortcut |
| 48 × 48 | Windows desktop, file explorer |
| 64 × 64 | High-DPI displays, app launchers |
| 128 × 128 | Modern browser bookmarks |
| 256 × 256 | Maximum size — browsers scale down as needed |
Best practice: Start with a 256×256 source image. Modern browsers are smart enough to scale a single high-resolution favicon to all needed sizes. If you want pixel-perfect control at every size, convert your source at multiple dimensions.
How to use your new favicon
- Convert your image to ICO using this tool
- Rename the downloaded file to
favicon.ico - Place it at the root of your website (e.g.,
/favicon.ico) - Optionally, add this to your HTML
<head>:<link rel="icon" type="image/x-icon" href="/favicon.ico">
After deploying, clear your browser cache or open your site in a private window to see the new favicon. Favicons are aggressively cached — updates may not appear immediately.
Input formats supported
- PNG — ideal for icons. Supports transparency, which is critical for favicons with non-rectangular shapes.
- JPEG — works but doesn't support transparency. Your favicon will have a solid background.
- WebP — modern format, good compression. Your browser will convert it cleanly.
- SVG — vector graphics rasterized at your chosen resolution. Great for logos.
Recommendation: Use a PNG with transparency for the best favicon. Your logo or icon on a transparent background produces the cleanest result.
Privacy: your icon, your machine
Unlike most online favicon generators, this tool never uploads your image to a server. The conversion happens entirely in your browser using the Canvas API. This matters even for icons — your source image may contain metadata, be your company logo before public launch, or simply be something you don't want sitting on a stranger's disk.