About ICO
ICO is the icon format Windows has used since its first version. Its key feature is that one file holds the same icon at several sizes, so Windows and browsers can pick a version drawn specifically for 16, 32 or 256 pixels instead of shrinking one large image. Since Windows Vista, those images can be stored as compressed PNG data, with full transparency.
Browsers adopted ICO for favicons in 1999, and still request /favicon.ico from every site by default.
Which sizes to include
For a favicon, 16, 32 and 48 pixels. For a Windows application or shortcut icon, add 256. Sizes in between, like 24 and 64, help in specific places but make the file bigger. Every size is drawn fresh from your original with careful downscaling.
Beyond the ICO
Modern sites need more than an ICO: an Apple touch icon, Android icons and a manifest. The favicon generator makes the whole set from one image.
ICO at a glance
| First released | 1985 |
|---|---|
| Compression | Holds PNG or BMP images |
| Transparency | Yes |
| Animation or pages | Several sizes in one file |
| Best for | Favicons and Windows icons |
| Support | Browsers and Windows |
Questions people ask
What size should an ICO file be?
Include 16, 32 and 48 px for favicons; add 256 px for Windows desktop icons.
Can I convert a JPG to ICO?
Yes, though JPGs have no transparency, so the icon will have a solid background.
How do I get a PNG out of an ICO?
Use ICO to PNG, which extracts every size inside the file.