ICO file format
Windows Icon (.ico): website favicons and Windows application or shortcut icons.
An ICO file bundles several square versions of the same icon — typically 16×16, 32×32 and 48×48 pixels, up to 256×256 — so Windows and browsers can pick the sharpest one for each place it is shown. It is still the most compatible format for a website favicon.
| Full name | Windows Icon |
|---|---|
| File extension | .ico |
| MIME type | image/x-icon |
| Created | around 1990 by Microsoft, for Windows |
| Compression | Lossless |
| Transparency | Yes |
| Animation | No |
| Colors | Several sizes (16×16 to 256×256) in one file, full alpha |
| Opens on | Windows, every browser (as a favicon) |
| Best for | website favicons and Windows application or shortcut icons |
Advantages
- Several sizes in one file
- Works as a favicon in every browser
- Transparency
Drawbacks
- Only square images up to 256×256
- Not useful outside icons
Convert ICO to…
Convert to ICO
Frequently asked questions
What is a .ico file?
An ICO file bundles several square versions of the same icon — typically 16×16, 32×32 and 48×48 pixels, up to 256×256 — so Windows and browsers can pick the sharpest one for each place it is shown. It is still the most compatible format for a website favicon.
How do I open a ICO file?
ICO files open on Windows, every browser (as a favicon). If a program will not open yours, convert it to a more common format.
Is ICO lossless?
Yes, ICO is lossless: no detail is lost when saving.
How do I convert ICO?
Use one of the converters below — they run in your browser, so your images are never uploaded. Most popular: ICO to JPG, ICO to PNG, ICO to WebP.