ICO (Windows Icon)
.ico · image/x-icon · 1985 · Microsoft
ICO is the Windows icon container from 1985, still relevant for one reason: favicons. An ICO file can pack multiple sizes (16×16, 32×32, 48×48…) so Windows and browsers pick the right one. EditItAll converts any image into a 256×256 ICO (with transparency preserved from PNG sources) suitable for favicon.ico. For modern sites, pair it with SVG and PNG icons.
Compression
Lossless
Transparency
Yes
Animation
No
Browser display
All browsers
Strengths & limitations
Strengths
- The one format every favicon pipeline accepts
- Multi-resolution container
- Transparency support
Limitations
- Max 256×256 pixels
- Useless outside icons
- Ancient, quirky structure
Best used for
- favicon.ico
- Windows application icons
- Legacy toolbars