What Is Base64 Encoding?
Base64 is a binary-to-text encoding that represents image bytes with printable ASCII characters. Three bytes of binary input become four Base64 characters, plus optional padding at the end. That is why the encoded payload is normally about one-third larger than the original binary file before the data URL prefix is added.
A data URL looks like data:image/png;base64,iVBORw0KGgo.... The media type tells the browser which image format to expect, ;base64 identifies the encoding, and the comma separates metadata from the encoded payload.
How to Convert an Image to Base64
- Step 1
Choose images
Drop or select up to 10 supported images. Each file can be up to 10 MB, with a 25 MB combined limit.
- Step 2
Choose an output
Select a data URL, HTML, CSS, JavaScript, JSON, Markdown, React, or Next.js snippet.
- Step 3
Copy or download
Copy the complete output, copy only the raw Base64 payload, or save the selected snippet as a text file.
When to Use Base64 Images
Good candidates
- Tiny icons and UI assets
- Single-file HTML documents
- Email templates with supported clients
- Small assets embedded in CSS
- Portable demos and test fixtures
- Data exchanged through a text-only format
Prefer an image file
- Photos, hero images, and banners
- Product galleries
- Images reused across several pages
- Responsive image sets
- Assets needing independent browser caching
- Performance- or discoverability-critical images
Base64 vs Traditional Image Files
| Feature | Base64 Data URI | External Image File |
|---|---|---|
| Network request | Embedded with its parent resource | Fetched from its URL |
| Transfer size | About 33% larger before compression | Original binary representation |
| Browser caching | Cached with HTML or CSS | Can be cached independently |
| Portability | Self-contained | Depends on a valid image URL |
| Responsive images | Awkward for srcset workflows | Works naturally with srcset and sizes |
| Best fit | Small, rarely reused assets | Most website imagery |
Raw Base64 vs a Data URL
Raw Base64 contains only the encoded payload. A data URL adds the data: scheme, the image MIME type, and the ;base64, marker. HTML image sources and CSS URLs normally need the complete data URL; APIs that already know the media type may request only the raw payload.
Decode mode accepts either form. For raw input, the tool inspects common file signatures to identify PNG, JPEG, WebP, GIF, AVIF, or SVG rather than assuming every payload is PNG. It also reports the decoded size and dimensions before download.
Continue Your Image Workflow
Reduce a large asset first with the Image Compressor, change its format with the Image Converter, optimize vector input with the SVG Converter, or encode ordinary UTF-8 text and files with the Base64 Encoder & Decoder.
Base64 and Data URL References
Base64 encoding and padding rules are defined by RFC 4648 . MDN documents the browser APIs used here in its FileReader.readAsDataURL reference and explains the data:[media-type];base64,data structure in its data URL guide . External references open in a new tab.