ICO to Base64
Use this free ICO to Base64 converter to turn any Windows Icon image into a Base64 string or a ready-made code snippet. Select a local .ico file (or paste a link to a remote one), pick the output format and press Encode ICO to Base64.
How to convert ICO to Base64 online
- Choose Local file and select a .ico file, or choose Remote URL and paste a link.
- Select the output format: plain Base64, data URI, HTML tag, CSS, JavaScript, JSON or XML.
- Click Encode ICO to Base64. The result appears instantly with a preview.
- Copy the result to the clipboard or download it as a .txt file.
About ICO (Windows Icon)
ICO is a container that stores one or more small images (commonly 16×16, 32×32 and 48×48) in a single file. Browsers have used favicon.ico for site icons since the late 1990s.
Embedding a favicon as a Base64 data URI in a <link rel="icon"> tag removes one HTTP request, which is a common trick for single-file HTML pages, offline apps and email templates.
| Developed | Microsoft |
|---|---|
| Contains | BMP or PNG images |
| Transparency | Yes |
| Typical use | Favicons, app icons |
| File signature | 00 00 01 00 |
Output formats
Choose how the result should be wrapped. The converter can return:
- txt: only the Base64 string, ready to paste into code, a database field or an API request.
- uri: a complete
data:URI that you can paste in a browser address bar or use anywhere a URL is accepted. - html img: an
<img>tag with the data URI insrc. - css background image: a CSS rule using
background-image: url(data:...). - html favicon: a
<link rel="icon">tag for an inline favicon. - html hyperlink: an
<a>link that downloads or opens the embedded file. - html iframe: an
<iframe>that renders the content inline. - javascript image: JavaScript that creates an
Imageobject. - javascript popup: JavaScript that opens the content in a new window.
- json: a JSON object with the file name, MIME type and data.
- xml: an XML element with the data inside a CDATA section.
Is it safe and how large will the result be?
Your file is never uploaded: it is read and converted locally by your browser using the File API, so even confidential documents stay on your device.
Base64 represents every 3 bytes with 4 characters, so the encoded result is about 33% larger than the original file (plus a few bytes for padding and the data URI prefix).
Frequently asked questions
How do I convert ICO to Base64?
Select your .ico file above and click "Encode ICO to Base64". The converter reads the file in your browser and outputs the Base64 string or a ready data URI.
What does a Base64-encoded ICO start with?
A ICO file encoded to Base64 typically starts with "AAABAA". As a data URI it begins with "data:image/x-icon;base64,".
Is there a file size limit?
There is no hard limit because the conversion runs locally, but very large files produce very long strings. Files up to about 50 MB work comfortably in modern browsers.
How do I convert the Base64 back to ICO?
Use the Base64 to ICO decoder: paste the string, and you can preview and download the original .ico file.
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