Base64 is a binary-to-text encoding scheme that converts arbitrary byte streams into an alphabet of 64 ASCII characters (A-Z, a-z, 0-9, +, and /). Because every 3 binary bytes (24 bits) are grouped into 4 six-bit chunks, the resulting ASCII string is consistently around 33% larger than the raw source image.

When combined with standard Data URI syntax (data:image/png;base64,...), browsers can render binary pictures directly from HTML source code or CSS stylesheets without initiating a separate network request to fetch an external file.

Best for Small Graphic Elements (< 10 KB): Loading spinners, logo badges, UI micro-icons, and placeholder thumbnails are prime candidates for Base64 inlining. Embedding these prevents layout shifts (CLS) on initial load.

Avoid for Large Photographs (> 20 KB): Inlining massive photos degrades initial HTML parse times and bloats page size. Additionally, inline Base64 data cannot be cached independently by browser HTTP caches or CDN edges.

Our encoder automatically detects and generates valid Data URIs for PNG, JPEG, WebP, SVG, GIF, AVIF, BMP, and ICO. You can copy HTML <img> tags, CSS background-image rules, Markdown syntax, or raw Base64 characters with a single click.