What is an ICO file?
ICO is the Windows icon format and the classic format for website favicons. A single .ico file can hold several sizes (16x16, 32x32, 48x48 up to 256x256) so the operating system or browser can pick the sharpest one.
| Full name | Windows Icon |
|---|---|
| File extensions | .ico |
| MIME type | image/x-icon |
| Introduced | 1985 |
| Compression | PNG or BMP inside |
| Transparency | Yes |
| Animation | No |
| Typical file size | Small |
| Best for | website favicons and Windows application icons |
| Compatibility | All browsers (favicon) and Windows |
How to open an ICO file
Windows
Shows as an icon in File Explorer; Photos and browsers can open it.
Mac
Preview opens ICO files and shows each size.
iPhone and iPad
Not supported for viewing; convert to PNG.
Android
Not supported by most apps; convert to PNG.
If none of these work, convert the file to a more widely supported format with one of the tools below.
Convert ICO files
Convert other files to ICO
ICO compared with other formats
- ICO vs PNG: ICO is a container for icons at several sizes (often PNGs inside). Use ICO for favicons and Windows shortcuts, PNG for everything else.
Frequently asked questions
What is an ICO file?
ICO is the Windows icon format and the classic format for website favicons. A single .ico file can hold several sizes (16x16, 32x32, 48x48 up to 256x256) so the operating system or browser can pick the sharpest one.
How do I open an ICO file on Windows?
Shows as an icon in File Explorer; Photos and browsers can open it.
How do I open an ICO file on a Mac?
Preview opens ICO files and shows each size.
Is ICO lossy or lossless?
ICO is lossless or uncompressed, so no detail is lost when saving.
Does ICO support transparency?
Yes: it supports transparent backgrounds.
How do I convert ICO to another format?
Use one of the free converters on this page, for example ICO to JPG, ICO to PNG, ICO to WebP. Files are converted in your browser without being uploaded.