What is an ICO file?
ICO is the icon format of Microsoft Windows and the classic format for website favicons - the little image in a browser tab. One ICO file can hold several sizes (16 × 16, 32 × 32, 48 × 48 and more), so the icon looks sharp everywhere.
ICO supports transparency, so icons can have rounded or irregular shapes. Modern sites often add PNG and SVG favicons too, but favicon.ico is still the universal fallback.
How to open an ICO file
Windows shows ICO files in File Explorer and opens them in Photos; Mac Preview opens them too. GIMP and online editors can edit them. To make one, convert a square PNG - or use the Favicon Generator for a complete set.
- Extension
- .ico
- Sizes
- Several in one file (16-256 px)
- Transparency
- Yes
- Best for
- Favicons, Windows icons