When to use Base64 images
- Tiny icons and logos in HTML emails, where external images are often blocked.
- Small images inside CSS to avoid an extra request.
- Embedding images in JSON or a single-file HTML document.
When not to
Base64 makes files about 33 % larger and cannot be cached separately, so keep it for images under a few kilobytes. Normal image files with good caching are better for photos.
The tool gives you the data URI, an <img> tag and a CSS background-image rule. Decode Base64 back to a file with the Base64 to Image Converter.
Frequently asked questions
Why is the Base64 string bigger than the image?
Base64 encodes 3 bytes as 4 text characters, which adds about 33 %.
Is there a size limit?
Images up to 10 MB can be encoded, but small images are recommended.
Is my image uploaded?
No, encoding happens in your browser.