What Is Image to Base64 Conversion?
Converting an image to Base64 transforms its binary data into a string of ASCII characters that can be embedded directly in text-based formats like HTML, CSS, and JSON. A Base64-encoded image wrapped in a data URI starts with data:image/png;base64, followed by the encoded string. This allows the image to be included inline — no separate HTTP request required.
How to Use This Converter
Click the upload area or drag an image onto it. The converter reads the file using your browser's FileReader API, generates the Base64 data URI, shows a preview, and displays the encoded string. Toggle between Data URI (includes the data:image/...;base64, prefix) and Base64 only (raw encoded string). Click Copy to copy to clipboard.
How Base64 Encoding Works
Base64 represents binary data using 64 ASCII characters (A–Z, a–z, 0–9, +, /). Every 3 bytes of binary data becomes 4 Base64 characters. This is why Base64-encoded data is always about 33% larger than the original binary. The = padding characters at the end align the output to a multiple of 4 characters.
The data URI format is: data:[MIME type];base64,[Base64 data]
When to Use Base64 Images
Good use cases
- Small icons and logos in single-file HTML documents — avoids an extra HTTP request.
- Email HTML templates — many email clients block external images but render inline data URIs.
- CSS backgrounds for tiny images like patterns, spinners, or decorative elements.
- API payloads — sending images as JSON data where file upload is not supported.
When to avoid
- Large images — the 33% size overhead bloats your HTML/CSS file, and the browser cannot cache the image separately from the page.
- Images used on multiple pages — a separate image file can be browser-cached; an inline data URI cannot.
How to Use a Base64 Image in Code
In HTML: <img src="data:image/png;base64,iVBOR...">
In CSS: background-image: url('data:image/png;base64,iVBOR...');
In JavaScript: img.src = 'data:image/jpeg;base64,/9j/4AAQ...';
Frequently Asked Questions
What is a Base64 data URI?
A string embedding an image directly in HTML/CSS without a separate file request. Format: data:image/png;base64, followed by the encoded data. Used for inline embedding where a file reference is inconvenient.
Is my image uploaded to a server?
No. This uses the browser's FileReader API to encode the image entirely client-side. The image never leaves your device, making it safe for private or confidential images.
What formats are supported?
Any image your browser can read: PNG, JPEG, GIF, WebP, SVG, BMP, ICO, AVIF. The MIME type is automatically detected and included in the data URI.
When should I use Base64 for images?
For small icons in single-file HTML, email templates that need inline images, and API payloads. Avoid for large images or images shared across pages — use external files with caching instead.
How do I use this in HTML?
Copy the Data URI and set it as the src attribute: <img src="data:image/png;base64,iVBOR...">. For CSS: background-image: url('data:...').