The favicon sizes browsers and devices actually want

A favicon used to mean one small 16×16 image. Now a browser tab, a phone's home screen shortcut, a bookmarks bar, and an Apple touch icon each expect their own size, and providing only one leaves some of those contexts either blurry or showing a generic fallback icon instead of yours.

Why one size isn't enough

A 16×16 icon scaled up to fill a 180×180 home-screen icon slot looks exactly as blocky as any small image stretched large — there's no way to add detail that wasn't there in the source. Each context a favicon shows up in has its own expected resolution, and modern practice is to provide a set of sizes rather than relying on a browser to badly upscale one small file.

The sizes worth covering

• 16×16 and 32×32 — the classic favicon sizes, used in browser tabs and bookmark lists on most desktop browsers.
• 180×180 — Apple's expected size for the home-screen icon when a page is added to an iPhone or iPad's home screen.
• 192×192 and 512×512 — used by Android and by web app manifests for home-screen icons and splash screens on installable web apps.

Keeping the design legible at 16px

Favicon Generator takes one source image and produces the full set of standard sizes at once, entirely in your browser — but no generator can fix a design that doesn't work at small sizes to begin with. Fine detail, thin lines, and small text disappear entirely at 16×16; a simple, bold shape or letterform that stays recognizable when shrunk down is what actually reads clearly in a browser tab, regardless of how many sizes get generated from it.