ICO (Windows Icon)

.ico · image/x-icon · 1985 · Microsoft

The favicon and Windows icon container format. Below is what ICO is best at, where it falls short, and how it compares — plus free, in-browser tools to convert ICO to and from other formats, with nothing uploaded.

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

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

Tools for ICO

ICO → PNG SVG → ICO PNG → ICO JPEG → ICO

Frequently asked questions

Is ICO lossy or lossless?+

ICO is lossless: it preserves every pixel exactly, with no quality loss.

Does ICO support transparency?+

Yes — ICO has an alpha channel, so it can store transparent areas. It is a still-image format (no animation).

Can browsers open ICO files directly?+

Yes — every mainstream browser displays ICO natively.

How do I open or convert a ICO file for free?+

Drop your ICO file into the EditItAll converter and choose an output format — it decodes and re-encodes entirely in your browser, with nothing uploaded, no account and no watermark.