Favicon ICO vs PNG
ICO and PNG are the two most common favicon formats. Choosing between them — or using both — depends on the browsers you need to support.
About Favicon ICO vs PNG
ICO and PNG serve different roles in favicon implementation, and most production websites use both together.
Favicon.ico: The .ico format was created specifically for Windows shell icons and became the de facto favicon standard in the early web. favicon.ico placed in the website root is automatically requested by browsers without any HTML tag required. It supports multiple internal resolutions (16×16, 32×32, 48×48) in one file. ICO is essential for IE, Edge Legacy, and ensuring the favicon works even when HTML tags are absent.
Favicon PNG: PNG favicons require an explicit link tag in the HTML head. They support full alpha transparency and are sharper on high-DPI displays when the correct size is referenced. PNG is the only format supported for Apple Touch Icons (180×180 for iOS home screen shortcuts). PNG files are smaller in size than equivalent ICO files for single resolutions.
Side-by-side comparison: | Feature | ICO | PNG | | Browser support | Universal including IE | Modern browsers | | Multiple sizes in one file | Yes | No (one file per size) | | Alpha transparency | Limited | Full | | Apple Touch Icon | No | Yes | | Dark mode support | No | No (use SVG) | | HTML tag required | No (auto-loaded) | Yes |
Best practice: serve favicon.ico at the root for universal fallback, add favicon-32x32.png via a link tag for modern browsers, and provide apple-touch-icon.png for iOS. Do not rely on ICO alone for modern sites — its alpha transparency support is inconsistent across rendering engines.