ICO to AVIF Converter

ICO to AVIF: What This Conversion Gives You

ICO is Microsoft's icon container — a directory of small bitmaps in one file, each entry recording its width and height in a single byte, which is why 256x256 is the ceiling and why Microsoft's own icon guidance stops there. AVIF is the AV1 Image File Format, published by the Alliance for Open Media in 2019, which stores AV1-coded pictures inside a HEIF-style ISO base media container. The conversion is straightforward and keeps transparency intact, but it comes with two honest caveats worth reading before you click: an icon is small, and at icon sizes AVIF is not automatically the smallest option.

ICO and AVIF Side by Side

How to Convert ICO to AVIF

1. Upload Your ICO File: Drag and drop your .ico onto the page or click "+ Add Files" to browse. Multi-size icon files are accepted and several can be queued at once.
2. Pick a Quality Preset: Open Advanced Options. "Quality Preset" starts at "Very High (Recommended)", which encodes at quality 95 on a 1-100 scale; "Highest" uses 100, and the steps below it trade fidelity for size down to 50.
3. Set a Size Target or Resolution (Optional): "Specific file size" encodes toward a byte target you type, with an "Auto Scale" switch that lets it reduce dimensions if quality alone cannot get there. "Image resolution" is on "Keep original" by default and also offers a percentage, a preset list that runs down to icon-scale values such as 256P, 128P, 64P, and 32P, or an exact Width x Height.
4. Convert and Download: Click "Convert" and download the .avif. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours. No sign-up, no watermark.

Where AVIF Wins and Where It Doesn't

AVIF's compression advantage comes from AV1's intra-frame prediction, and that advantage grows with image area. At icon dimensions there is barely any area to work with, while the container still has to carry its box structure, colour-property boxes, and an alpha auxiliary item. A 64x64 test icon encoded at the default preset came out slightly larger as an AVIF than the same picture saved as a PNG — the format is doing nothing wrong, there simply is not enough image for it to win on.

Common Errors and How to Fix Them

• "The AVIF came out at 16x16." A multi-size .ico is a directory of bitmaps and the decoder reads the first entry, not the biggest — many icon editors write the smallest first. Re-save the icon containing only the size you want, or convert from the original artwork.
• "The AVIF is bigger than my PNG." Normal at icon dimensions. AVIF's fixed container cost is a large share of a file that is only a few hundred bytes of picture. Use PNG below roughly 128 pixels and keep AVIF for larger art.
• "The image will not open in my editor." AVIF support in desktop image editors is still uneven even though browsers handle it. Convert to something universal with AVIF to PNG if a tool refuses it.
• "It looks soft after I enlarged it." Setting a resolution preset above the icon's own size is an upscale. The pixels are being stretched, not refined — start from the source artwork if you need a large, crisp image.
• "Older browsers show nothing." Serve AVIF inside a <picture> element with a PNG or WebP fallback so browsers below the versions listed above still get an image.

Frequently Asked Questions

Does my icon's transparency survive the conversion to AVIF?

Yes. AVIF stores alpha as a separate auxiliary image, and the 32-bit RGBA entries inside modern icon files carry their 8-bit alpha channel across intact — including partially transparent anti-aliased edges. There is no Background Color control on this page precisely because nothing needs flattening. If your icon uses only the older 1-bit AND mask, the hard-edged transparency in the source is what you get in the output.

My ICO holds several sizes — which one becomes the AVIF?

The first image stored in the file. An .ico is a directory of bitmaps at different sizes and colour depths, and the decoder reads entry zero rather than searching for the largest. Because icon editors often write entries smallest-first, a favicon bundling 16x16 through 256x256 can convert at 16x16. If the output is smaller than you expected, export the size you want as its own image and convert that.

Can I use an AVIF as my favicon?

Not dependably. Browsers still fetch /favicon.ico by default, and the well-supported alternatives declared through <link rel="icon"> are PNG and SVG. Treat this conversion as a way to bring icon artwork into an AVIF image pipeline, not as a favicon workflow — to build an actual favicon, go the other way with PNG to ICO.

Will converting to AVIF make my icon sharper?

No. Every icon entry is at most 256x256 pixels and most are 16, 32, or 48 pixels across. AVIF is an efficient way to store what is there; it cannot reconstruct detail that was never drawn. Choosing a larger output resolution enlarges the same pixels and softens the edges. For a crisp large graphic, convert from the original artwork rather than from the icon.

What does the Quality Preset actually set?

A quality value on a 1-100 scale passed to the AVIF encoder: "Very High (Recommended)" is 95, "Highest" is 100, then 90, 80, 70, 60, and 50 for the presets below. On flat icon artwork the difference between 95 and 100 is generally invisible while the file size difference is real, which is why 95 is the default.

How does "Specific file size" work on such a small image?

It encodes toward the byte target you enter, searching quality settings to land under it, and the "Auto Scale" switch additionally permits reducing the pixel dimensions when quality alone cannot reach the target. On an icon this rarely matters — the file is already a few kilobytes — but it is useful when a CMS or an ad specification imposes a hard byte ceiling.

Should I convert my icon to AVIF or to WebP?

WebP is the safer middle ground for small graphics: it supports alpha, handles flat colour well, and is supported by a wider range of desktop tools. AVIF pulls ahead on larger images and on photographic content. For a 256x256 logo on a site that already serves AVIF, AVIF is a reasonable pick; for a 32x32 sprite, ICO to WebP or plain PNG will serve you better.

How are my uploaded icons handled?

Every file is uploaded over an encrypted connection, decoded and re-encoded on our servers, and deleted automatically a few hours later. There is no sign-up, no watermark, and files are never shared or made public. Icons are measured in kilobytes, so both the upload and the resulting AVIF are small.