What is an ICO file?
That tiny picture in your browser tab has a format all its own. ICO is the classic Windows icon container — the format behind favicons, desktop shortcuts, taskbar icons, and application icons. A single ICO file can hold several sizes of the same image, and modern ICO files store each size as a compact PNG compressed inside the container, which keeps the file small while preserving full transparency. Converting your PNG to ICO takes seconds: pick a size below and you get a proper .ico file ready to use as a favicon or a Windows icon, with transparency intact and no software to install.
Which size should you choose?
- 16 × 16 — the classic browser-tab favicon and address-bar icon.
- 32 × 32 — desktop icons, the Windows taskbar, and retina-display favicons.
- 48 × 48 — large icon views in Windows Explorer.
- 64 and 128 — high-DPI tiles, app launchers, and crisp scaling.
- 256 × 256 — extra-large views; the biggest size the ICO format records (stored as 0 per the spec).
This tool writes the single size you select into the file. If you need several sizes bundled in one .ico, convert once per size and combine them with an icon editor — or simply pick 256, which operating systems scale down cleanly. Whatever you choose, start from the largest, squarest source PNG you have: downscaling a big sharp image always beats upscaling a small one.
How to convert PNG to ICO
- Drop your PNG onto the dashed box above, or click it to browse your files.
- Pick an icon size from the dropdown — 32 × 32 is the best all-rounder.
- Press Convert to ICO and download your
.icofile.
Your image is resized to an exact square at the chosen size and packaged as a PNG-compressed entry inside a standard ICO container — the same structure Windows itself produces. The before-and-after preview shows your original next to the icon-sized result, so you can check that fine details and text remain legible at small sizes before you download.
Using your new icon
For a website favicon, save the file as favicon.ico, place it at the root of your site, and reference it with <link rel="icon" href="/favicon.ico"> — every browser will pick it up. For a Windows shortcut or folder, right-click it, open Properties, and use the Change Icon button to point at your new .ico file. Because the icon keeps your PNG's alpha channel, rounded logos and non-rectangular artwork sit cleanly on any background, from light browser tabs to dark taskbars.