What is a Base64 data URI?

A data URI embeds image data directly into HTML or CSS using Base64 encoding. The format is data:image/png;base64,iVBOR... This eliminates an HTTP request but increases the document size by about 33%.

When should I use Base64 data URIs instead of image files?

Data URIs work best for small images like icons, logos, and decorative elements under 10KB. They reduce HTTP requests but increase HTML/CSS file size by 33%. For larger images, separate files with proper caching are more efficient.

Is my image data private when using this tool?

Yes. Everything runs entirely in your browser using the FileReader API. Your images are never uploaded to any server. No data leaves your device.

Image to Base64 Encoder

Convert images to Base64 data URIs or decode Base64 strings back to images. Everything runs in your browser.

Drop an image here or browse

PNG, JPG, WebP, GIF, SVG

Paste Base64 string or data URI

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). When applied to images, it converts the raw file bytes into a text string that can be embedded directly in HTML, CSS, or JSON without needing a separate file.

A Base64-encoded image is wrapped in a data URI format: data:image/png;base64,iVBORw0KGgo.... The browser reads this inline data and renders the image just like it would from an external URL.

When to Use Data URIs

Inline images in HTML emails - Email clients often block external images. Data URIs embed the image directly in the message body.

Small icons and logos - For images under 5-10KB, a data URI eliminates an extra HTTP request, which can improve initial page load.

CSS background images - Embed tiny decorative patterns or UI elements directly in your stylesheet.

Single-file HTML documents - When you need to distribute a self-contained HTML file, data URIs keep everything in one file.

Base64 Size Overhead

Base64 encoding increases data size by approximately 33%. Every 3 bytes of input produce 4 bytes of output. For example, a 10KB image becomes roughly 13.3KB as a Base64 string. This overhead is important to consider:

Original Size	Base64 Size	Overhead
1 KB	~1.33 KB	+0.33 KB
10 KB	~13.3 KB	+3.3 KB
100 KB	~133 KB	+33 KB
1 MB	~1.33 MB	+0.33 MB

Original Size

Base64 Size

Overhead

1 KB

~1.33 KB

+0.33 KB

10 KB

~13.3 KB

+3.3 KB

100 KB

~133 KB

+33 KB

1 MB

~1.33 MB

+0.33 MB

Factor	Data URI	External File
HTTP requests	None (inline)	1 per image
Caching	Not cached separately	Cached by browser
File size	33% larger in document	Original size
Maintenance	Harder to update	Replace file on server
Best for	Small, rarely changed images	Large or frequently updated images

Factor

Data URI

External File

HTTP requests

None (inline)

1 per image

Caching

Not cached separately

Cached by browser

File size

33% larger in document

Original size

Maintenance

Harder to update

Replace file on server

Best for

Small, rarely changed images

Large or frequently updated images

Frequently Asked Questions

Does Base64 encoding change image quality?

No. Base64 is a lossless encoding. The decoded image is bit-for-bit identical to the original. No pixels are altered during the encode/decode process.

What image formats can I convert?

This tool accepts PNG, JPEG, WebP, GIF, and SVG files. The resulting data URI preserves the original MIME type, so the browser knows how to render it correctly.

Is there a size limit?

There is no hard limit in this tool since processing happens in your browser. However, data URIs over 100KB are generally not recommended for production use. Large inline images bloat your HTML, cannot be cached independently, and slow down page parsing.

Is my image data private?

Yes. The entire conversion happens locally in your browser using the JavaScript FileReader API. Your images are never uploaded to any server. No data leaves your device.