Image ↔ Base64 Converter

Understanding the Image to Base64 Converter

A bidirectional Image ↔ Base64 converter that runs entirely in your browser. Encode PNG, JPG, WebP, GIF, or SVG images into Base64 data URIs with ready-to-copy HTML <img> and CSS background snippets, or paste a Base64 string to decode and preview it as an image. All processing happens client-side—your images never leave your browser.

How it works

The encoder uses the browser's FileReader API to read the uploaded image as a data URL, which natively encodes it as Base64 with a MIME-type prefix. For decoding, the tool parses the Base64 input (detecting raw Base64 or data URI formats), normalizes it to a data URI, and validates it by loading it into an Image object. The tool calculates file sizes without full allocation: Base64 length is reverse-computed from character count using the formula (length × 3) / 4 minus padding bytes, and the data URI size is measured via TextEncoder.

Tips & common mistakes

• For small icons and logos, embedding Base64 reduces HTTP requests but increases HTML/CSS size; test whether the data URI or separate file is faster for your use case.
• The tool auto-detects image format when decoding; paste raw Base64 without the data: prefix and it assumes PNG, or provide the full data URI to specify WebP, GIF, etc.
• Base64 strings are roughly 33% larger than the original binary; a 3 MB image becomes ~4 MB as Base64, so embedding very large images is inefficient.
• Copy the ready-made HTML <img> and CSS background snippets directly—the tool handles all encoding and formatting automatically.
• Whitespace in pasted Base64 is automatically stripped, so copying from formatted sources or across multiple lines works without cleanup.
• Downloaded images from decoded Base64 are detected by their MIME type in the data URI; SVG files are saved with .svg extension, JPEG as .jpg, others as their native extension.

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