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ICO to Base64 Converter

Encode .ico favicon files as Base64 data URLs for inline HTML favicons or web manifests

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What is ICO to Base64 Converter

Written by Giorgos Kostas. Last reviewed:

ICO is the Windows icon container that holds one or more raster images (typically 16×16, 32×32, 48×48). It is still the most broadly supported favicon format.

ICO to Base64 Encoder takes a .ico file and returns a `data:image/x-icon;base64,…` data URL you can drop directly into `<link rel="icon" href="…">` or a CSS rule.

Why use it

  • Ship a single-file HTML artifact that includes its own favicon.
  • Inline a favicon in a sandboxed preview (like a Storybook or playground).
  • Paste the result into an email-template field that cannot reference external assets.
  • Encoding is 100% in-browser — no upload.

Features

  • Multi-resolution ICO support
  • Byte-for-byte encoding
  • Copy data URL or raw Base64
  • Drag-and-drop ICO upload
  • ICO processed in your browser
  • Largest-frame ICO preview

How to use ICO to Base64 Converter

  1. Drop an ICO. Drag a .ico file into the tool or click Choose ICO.
  2. Copy the data URL. Copy `data:image/x-icon;base64,…` or the raw Base64.
  3. Embed it. Paste it into `<link rel="icon" href="…">` or a CSS rule.

Example (before/after)

ICO file

favicon.ico (binary, 4 KB, 32×32)

Base64 data URL

data:image/x-icon;base64,AAABAAIAEBAAAAEAIABoBAAAJgAAACAgAAABACAAqBAAAI4EAAAoAAAAEAAAAC…

Common errors

Wrong MIME type

Some tools output `image/vnd.microsoft.icon` while others use `image/x-icon`.

Fix: Both are valid; we emit `image/x-icon` because it is the most widely supported in browsers.

Multi-resolution icons are truncated

Tools that rasterize through a canvas drop the extra sizes in a multi-res ICO.

Fix: This tool encodes the file byte-for-byte, so every embedded size is preserved.

FAQ

Does it preserve multiple icon sizes?

Yes. Encoding is byte-for-byte, so every image frame in a multi-resolution ICO survives.

Are files uploaded?

No. The encoding happens entirely in your browser.

Which MIME type should I use?

Use `image/x-icon` for maximum compatibility. `image/vnd.microsoft.icon` is technically more correct but less widely recognized.

Can I decode it back to a .ico?

Yes — paste the data URL into the Base64 to Image tool; it auto-detects `image/x-icon` and produces a downloadable file.

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Related favicon and encoder tools: You can also browse the full Encoders & Decoders category for more options.

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