How to Convert ICO to AVIF: Step-by-Step Tutorial

By Bill Crawford  ·  March 2026  ·  6 min read  ·  Last updated March 6, 2026

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What This Tutorial Covers

This tutorial walks through converting ICO icon files to AVIF format using the free browser-based converter at Data Conversion Center. You will learn how to upload files, configure quality settings, use batch mode, download results individually or as a ZIP, and troubleshoot common issues. No software installation required — everything runs in your browser.

Before You Start

You need:

• One or more ICO files you want to convert
• A modern browser: Chrome 85+, Firefox 93+, or Edge 121+ for AVIF output. Safari 16.4+ also works but AVIF encoding via canvas may fall back to WebP in some configurations — check the compatibility notice at the top of the tool.

Step 1: Open the Converter

Navigate to dataconversioncenter.com/image-tools/ico-to-avif/. The tool loads entirely in your browser — no sign-in, no installation, no file size limits from a backend. If your browser does not support AVIF encoding via the Canvas API, a yellow compatibility warning will appear at the top of the tool, and your output will be saved as WebP instead of AVIF.

Step 2: Upload Your ICO Files

You have two options for adding files:

• Drag and drop: Drag one or more .ico files from your file manager directly onto the drop zone. The zone highlights blue when you hover over it.
• Browse: Click anywhere on the drop zone or the "Browse Files" link to open a file picker. You can select multiple files at once using Shift+click or Ctrl+click.

As files are added, thumbnail previews generate automatically using your browser's built-in ICO decoder. Each card shows the filename, file size, and a "Ready" status badge. If a file cannot be decoded (for example, a corrupt ICO or a file with an incorrect extension), it will be skipped and a warning will appear briefly below the drop zone.

Step 3: Adjust Quality (Optional)

The Quality slider above the Convert button defaults to 80 — a good balance between file size and visual quality for most icon art. Here is when to adjust it:

• Use 85–95 for logo art, icons with thin lines or text, or any icon where you need to preserve fine detail. The higher quality prevents compression artifacts at the small sizes typical of icon display.
• Use 75–80 for general web icons where some compression is acceptable. This is the default range and works well for most icon conversions.
• Use 60–75 only if you need very small files and the icon will be displayed at larger sizes where artifacts are less noticeable.

Drag the slider left to reduce quality (and file size) or right to increase quality. The number to the right of the slider updates in real time.

Step 4: Choose ZIP or Individual Download

Check the "Download as ZIP" checkbox if you want all converted files bundled into a single archive. If unchecked, each AVIF file will download separately. For batch conversions of more than five files, ZIP mode is recommended to avoid browser download notification clutter.

Step 5: Convert

Click the Convert to AVIF button. The tool processes files in parallel batches of two, updating the progress bar and each card's status badge in real time. Status badges cycle through: Ready → Converting → Converted (green) or Error (red).

For a batch of 10 ICO files, conversion typically completes in 2–5 seconds depending on your device. Larger ICO files with higher-resolution frames take slightly longer because the canvas encode step scales with image area.

Step 6: Download Results

Once conversion completes, the output section appears below the progress bar. Each card in the output grid shows the AVIF filename, output file size, and a Download button.

• Individual download: Click the "⬇ Download AVIF" button on any card to download that file immediately.
• Bulk download: Click "Download All AVIFs" at the bottom to trigger individual downloads for all converted files, or "Download ZIP" if you enabled the ZIP checkbox. The ZIP is named dataconversioncenter_ico_to_avif_YYYYMMDDHHMM.zip using your local time.

After downloading, the tool automatically resets after a short delay. You can also click "Start Over" at any time to clear all files and begin a new batch.

Troubleshooting Common Issues

File skipped with "not a valid ICO file" warning. The tool checks both the file extension and MIME type. If the file has a different extension or your OS reported an incorrect MIME type, rename the file to end in .ico and try again.

Output is WebP instead of AVIF. This means your browser does not support AVIF encoding via the Canvas API. The tool automatically falls back to WebP. Upgrade to Chrome 85+, Firefox 93+, or Edge 121+ for AVIF output. The compatibility warning at the top of the page will indicate this in advance.

ICO thumbnail does not load. Some ICO files — particularly very old ones with BMP frames only — may not render thumbnails correctly due to browser differences in ICO decoding. The conversion will still proceed; if it succeeds, the AVIF output will be generated from whatever the browser could decode.

Artifacts visible in output. If you see blocky or blurry areas in the AVIF, increase the quality slider to 90 or higher and reconvert. Icon art with fine lines and flat colors is more sensitive to compression artifacts than photographs.

Conversion fails with "Error" badge. This typically indicates the ICO file could not be decoded by the browser's Canvas API. Try opening the file in another image viewer to confirm it is not corrupt. If the ICO file is valid but conversion still fails, try a different browser.

Using the AVIF Output on the Web

Once you have your AVIF file, use it in HTML with progressive fallback for older browsers:

<picture>
  <source srcset="icon.avif" type="image/avif">
  <source srcset="icon.webp" type="image/webp">
  <img src="icon.png" alt="Brand icon" width="64" height="64">
</picture>

This pattern delivers AVIF to supporting browsers, falls back to WebP for older browsers that support WebP but not AVIF, and uses PNG as the final fallback for maximum compatibility.