Convert ICO to AVIF — Smallest Web File

An ICO is a multi-resolution container for a square mark. AVIF compresses it harder than WEBP or PNG while still carrying an alpha channel, which makes it the smallest way to publish an icon as an ordinary image.

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HEIC, WEBP, AVIF, TIFF, BMP, SVG, GIF, PNG, JPG, PDF, CR2, NEF, ARW, DNG — up to 50MB each, or 50 from a folder

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Preset:
Common
Modern
Legacy
Other

Modern format with excellent compression. Limited browser support.

Apple's format. Excellent quality at small sizes.

Lossless format. Large files, ideal for print/archival.

256 colors max. Best for simple graphics.

Uncompressed bitmap. Very large files.

Vector trace. Best for logos and simple graphics. Not a pixel-perfect conversion.

Smart
Manual

SSIM-optimized — finds the lowest file size at your chosen visual fidelity.

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Upscaling uses Lanczos interpolation (max 4x). Results may appear softer on images enlarged beyond 2x.

Resize tool → Live preview, percentage scaling, and dimension presets.

Tip: Use PNG or WebP for transparent output. Standalone tool →

Click or drop logo (PNG/JPG/WEBP, max 5MB)

Lossless format — files can be large

GIF is limited to 256 colors

Best for logos, icons, and line art. Photos produce stylized results.

BMP files are uncompressed and can be very large. Consider TIFF (LZW) or PNG for lossless with smaller file sizes.

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ICO vs AVIF Comparison

Feature ICO AVIF
Full Name Icon File Format AV1 Image File Format
Lossy Compression
Lossless Compression
Transparency
Animation
Browser Support All browsers (favicon) Chrome 85+, Firefox 93+, Safari 16.4+
Color Depth 16.7M (24/32-bit) 16.7M+ (up to 12-bit HDR)
Typical Use Website favicons, Windows application icons Next-gen web images (even smaller than WEBP)
Year Introduced 1985 2019

Why Convert ICO to AVIF?

AVIF is smaller again than WEBP and still carries alpha. For a logo used across a site it is the least bandwidth for the same appearance, provided every consumer is a modern browser.

How to Convert ICO to AVIF

1

Upload your .ico file.

2

The largest icon entry is extracted and re-encoded with AV1, keeping transparency.

3

Download the AVIF. Encoding takes a moment longer than PNG; the file is smaller.

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Quality Note

AVIF handles the flat colour and hard edges of icon artwork well, but at these pixel dimensions the absolute saving is small. The reason to choose it is consistency with the rest of a site's images.

Frequently Asked Questions

Only for consistency. AVIF is the smallest format at a given quality, but on a 256-pixel mark the absolute saving is a few kilobytes. It makes sense when everything else on the site is already AVIF.

Yes, AVIF carries a full alpha channel, so the mark keeps its transparent background and its soft edges. That puts it alongside PNG and WEBP rather than JPG.

Not reliably. Browser support for AVIF in the favicon slot lags well behind support for AVIF in ordinary images, so keep an .ico or PNG for the tab icon and use AVIF elsewhere on the page.

AVIF uses AV1 compression, which evaluates a large number of encoding options regardless of how small the image is. The search is fixed overhead rather than something that scales down with the pixels.
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