The Complete Favicon Guide: Every Size, Format, and File You Actually Need

You need multiple sizes, not one. The classic favicon.ico should contain 16×16 and 32×32 pixel versions bundled together. For modern browsers, also provide a 32×32 PNG. For Apple devices (iPhone/iPad home screen), you need a 180×180 apple-touch-icon.png. For Android home screen and PWAs, you need icons at 192×192 and 512×512. Optionally, for Windows tiles and other contexts, additional sizes may help. The minimum viable set that covers everything: favicon.ico (multi-size), 32×32 PNG, 180×180 Apple touch icon, and 192×192 + 512×512 for web manifest.

ICO is a container format that can hold multiple image sizes in one file — most commonly 16×16 and 32×32. Historically it was the only favicon format browsers supported. PNG is a single image at one specific size. Modern browsers support PNG favicons directly with a link tag, but the browser's direct request for /favicon.ico (which happens even without a link tag) only works with .ico files. Best practice is to have both: favicon.ico in your site root for the automatic browser request, plus PNG variants referenced in HTML link tags for more contexts.

If your site is ever added to a mobile home screen, or if you're building a Progressive Web App, yes. The manifest.json file lets you specify app icons, theme colors, and other properties. Without a manifest, Android Chrome uses whatever icon it finds, often the favicon at low resolution, which looks bad on home screens. A basic manifest with 192×192 and 512×512 icons covers home screen icons on Android Chrome and Firefox for Android. iOS uses apple-touch-icon.png separately, independent of the manifest.