AVIF to Base64
Use this free AVIF to Base64 converter to turn any AV1 Image File Format image into a Base64 string or a ready-made code snippet. Select a local .avif file (or paste a link to a remote one), pick the output format and press Encode AVIF to Base64.
How to convert AVIF to Base64 online
- Choose Local file and select a .avif 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 AVIF to Base64. The result appears instantly with a preview.
- Copy the result to the clipboard or download it as a .txt file.
About AVIF (AV1 Image File Format)
AVIF stores images compressed with the AV1 video codec inside a HEIF container. It offers excellent quality at very small sizes, often beating WebP by another 20% or more.
AVIF is supported by all major browsers released since 2024. If file size is your main concern when embedding images as Base64, AVIF is currently the most efficient choice.
| Developed | 2019, Alliance for Open Media |
|---|---|
| Compression | Lossy and lossless (AV1) |
| Transparency | Yes |
| HDR / wide gamut | Yes |
| File signature | ....ftypavif |
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 AVIF to Base64?
Select your .avif file above and click "Encode AVIF 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 AVIF start with?
A AVIF file encoded to Base64 typically starts with "AAAAHGZ0eXBhdmlm". As a data URI it begins with "data:image/avif;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 AVIF?
Use the Base64 to AVIF decoder: paste the string, and you can preview and download the original .avif file.
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