What is an ICO file?
ICO is the Windows icon format. One ICO file can bundle the same icon at several sizes, typically 16, 32 and 48 pixels and up to 256, and it's still the classic format for website favicons.
- Full name
- Windows Icon
- File extensions
- .ico
- MIME type
- image/x-icon
- Type
- Raster image
- Compression
- Lossless
- Transparency
- Yes
- Animation
- No
- Format Hero support
- Convert to only
What ICO is used for
Website favicons (favicon.ico) and Windows application and shortcut icons.
Strengths
Several sizes in one file, transparency, and support in every browser as a favicon.
Weaknesses
Limited to 256 × 256 pixels and only useful for icons. Most image apps don't treat it as a regular image format.
Compatibility
Every browser accepts favicon.ico, and Windows uses ICO for application and shortcut icons. Support in image editors is uneven.
Creating ICO files
Format Hero can create ICO files from PNG, JPG, PDF or HEIC and other images, but it can't open existing ICO files yet.
Convert other formats to ICO
Questions
How do I open an ICO file?
Browsers and Windows display ICO files directly. To edit one, use an image editor with ICO support such as GIMP.
Is ICO lossy or lossless?
ICO is lossless: every pixel is stored exactly.
Does ICO support transparency?
Yes. ICO supports full transparency, including soft edges and shadows.
Can Format Hero convert ICO to PNG?
Not yet. Format Hero can create ICO files from other images, but it can't read existing ICO files.