Frequently Asked Questions
What is an ICO file?
ICO is the icon file format used by Microsoft Windows and web browsers for favicons. It can store multiple image sizes (e.g. 16×16, 32×32, 48×48, 128×128) in a single file so the OS or browser picks the most appropriate size for each context.
Are my images uploaded to a server?
No. Everything runs entirely in your browser using the HTML5 Canvas API. Your PNG files are never sent to any server — the conversion is 100% client‑side. The privacy badge above confirms this.
What sizes are generated?
This tool generates five standard favicon sizes: 16×16, 32×32, 48×48, 64×64, and 128×128 pixels. These cover all major use-cases — browser tabs, taskbars, bookmarks, Windows desktop, and high‑DPI displays.
Can I use a non‑square image?
Yes. The tool preserves your original aspect ratio by rendering into a square canvas with transparent padding. The resulting favicon will display correctly in all modern browsers and operating systems.
How do I use the generated ICO in my website?
Place the .ico file in your site root and add <link rel="icon" type="image/x-icon" href="/favicon.ico"> inside the <head> of your HTML. The snippet is automatically shown after conversion and can be copied with one click.
Why does my transparent background appear as black in some viewers?
Some older icon viewers do not support alpha transparency in ICO files. Modern browsers render transparency correctly. The ICO format stores a 32‑bit BGRA bitmap per size, and this tool writes proper alpha channel data.