What is PNG to ICO?
ICO is the format used for Windows icons and a website’s favicon.ico, and it can hold several sizes in one file. This tool turns your PNG into a favicon.ico with 16/32/48 px sizes, entirely in your browser with no upload.
How to use it
- Select or drop in a PNG (square with a transparent background is ideal).
- The tool generates a multi-size preview instantly.
- Click Download to get favicon.ico.
Handy tips
- Clean up your logo first (background removal or PNG to SVG) for a sharper favicon.
- At 16px the icon is tiny — fewer details read more clearly.
- Name it
favicon.icoin your site root to be auto-detected.
An ICO holding three images, 30× smaller than one PNG — how?
Because the three images inside are tiny. The output packs 16, 32 and 48 px side by side (those three sizes are fixed in the source, and each slot stores a PNG stream), 3,584 pixels in total. The 1200 × 800 logo it came from has 960,000 — 268× more. The bytes go 28.8 KB → 951 B (-97%), a factor of only 31. Two different factors, and the gap is the finding: per pixel, the ICO is 8.6× more expensive. Small images cannot amortise their own overhead — three PNG streams each carry a header, and the ICO directory sits on top. The illustration row behaves the same way: 34.7 KB → 1.3 KB (-96%). One behaviour to expect on shape: scaling takes the smaller ratio and centres the result, so a non-square source keeps its aspect and gains transparent margins inside the square rather than being squashed.