Image to Base64 Converter

Base64 turns an image file into plain text, so it can sit inside HTML, CSS, JSON, Markdown or an email template as a data URI instead of being loaded as a separate file. Choose any image — PNG, JPG, GIF, WebP, AVIF, SVG, ICO or BMP — and copy the raw Base64, a ready data URI, a CSS background rule, an HTML <img> tag or a Markdown image. The file is read on your device and never uploaded.

How to use this tool

1. Choose one or more image files.
2. Pick the output: data URI, raw Base64, CSS, HTML <img>, Markdown, or all of them.
3. Optionally type alt text for the HTML and Markdown snippets.
4. Press Copy result, or download the .txt file offered for very large images.

Formula

Base64 length = 4 × ⌈bytes ÷ 3⌉; data URI = data: + MIME type + ;base64, + Base64

Every 3 bytes become 4 characters from the 64-character alphabet of RFC 4648, so the text is about 33% bigger than the file, a little more for tiny files because of the "=" padding. The MIME type is read from the file's first bytes (its magic number) when they are recognised, because file names and reported types are sometimes wrong; otherwise the browser's type or the extension is used.

Example

The 163-byte test SVG (120 × 80 px) becomes 4 × ⌈163 ÷ 3⌉ = 220 Base64 characters, 35% more than the file, starting PHN2ZyB4bWxucz0i. The data URI adds the 26-character prefix data:image/svg+xml;base64, for 246 characters in total, and the HTML snippet gets width="120" height="80" read from the image itself.