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Read guide →Convert to Base64
Encode an image as a Base64 string you can paste into CSS, JSON, or an HTML attribute, generated on your own device.
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Reviewed 2026-08-15
Free Convert Image to Base64 – how it works
Base64 rewrites binary data using 64 printable characters, which lets an image travel inside a text format. That is how an icon ends up embedded in a stylesheet, a JSON payload, or an email template rather than being fetched as a separate file.
The output here is the raw Base64 string without a prefix. If you need a data URI ready to drop into a src or a background-image, use Image to Data URI instead, which returns the same payload with the data:image/png;base64, prefix already attached.
The encoding step grows the data by roughly a third, because three bytes of input become four characters of output. That overhead is the reason to keep this for small assets. Inlining a photograph bloats your HTML or CSS and, unlike a linked file, an inlined image cannot be cached separately by the browser.
How to use Convert Image to Base64 online
- Add the image. Drop in the file you want to inline. Small icons, logos, and simple graphics are the sensible candidates.
- Copy the string. The Base64 text appears ready to copy. It is the payload only, with no data URI prefix.
- Paste it where it is needed. Drop it into your CSS, JSON, template, or API request. Add the data:image/png;base64, prefix yourself if the destination expects a full data URI.
When to use it
- Inline a small icon in CSS to avoid an extra network request.
- Embed an image in a JSON payload for an API that takes no file uploads.
- Put a logo directly into an HTML email template.
- Include a test image in a script or fixture without shipping a binary file.
Known limitations
- Base64 adds about 33 percent to the data size, so inlining anything large makes the containing file noticeably heavier.
- Inlined images cannot be cached independently, which means a change to one icon invalidates the whole stylesheet or document that contains it.
- Output is encoded as PNG. Photographs will produce a much longer string than the equivalent JPEG would.
Frequently asked questions
When should I inline an image as Base64?
For assets of a few kilobytes where saving a request matters more than caching, such as a small icon in CSS or a logo in an email. Anything larger is better served as a normal file.
What is the difference between Base64 and a data URI?
Base64 is the encoded payload. A data URI is that payload with a scheme and MIME type in front, like data:image/png;base64,iVBORw0. Use Image to Data URI if you want the complete form.
Are my images uploaded to a server?
No. The work happens in the page using the Canvas API and WebAssembly, so the file is read straight from your disk into the tab. Nothing is transmitted and there is no copy on a server to worry about.
Does Base64 make the image smaller?
No, the opposite. It grows by roughly a third, since every three bytes become four characters. Base64 exists to make binary data safe in text, not to compress it.
Which output format is used?
PNG, which is lossless and handles transparency. For a photograph that produces a long string, so compress it with Compress JPG first if size is a concern.
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