BMP to Base64
Use this free BMP to Base64 converter to turn any Bitmap Image File image into a Base64 string or a ready-made code snippet. Select a local .bmp file (or paste a link to a remote one), pick the output format and press Encode BMP to Base64.
How to convert BMP to Base64 online
- Choose Local file and select a .bmp file, or choose Remote URL and paste a link.
- Select the output format: plain Base64, data URI, HTML tag, CSS, JavaScript, JSON or XML.
- Click Encode BMP to Base64. The result appears instantly with a preview.
- Copy the result to the clipboard or download it as a .txt file.
About BMP (Bitmap Image File)
BMP is the native Windows bitmap format. Pixels are usually stored uncompressed, so files are large but trivial to read and write, which keeps BMP popular in embedded systems and legacy software.
Because BMP is uncompressed, encoding it to Base64 produces a very long string. If you only need to display the image on a web page, converting it to PNG first will make the Base64 output dramatically shorter.
| Developed | Microsoft, Windows 1.0+ |
|---|---|
| Compression | Usually none (optional RLE) |
| Transparency | Limited (32-bit variants) |
| Animation | No |
| File signature | 42 4D ("BM") |
Output formats
Choose how the result should be wrapped. The converter can return:
- txt: only the Base64 string, ready to paste into code, a database field or an API request.
- uri: a complete
data:URI that you can paste in a browser address bar or use anywhere a URL is accepted. - html img: an
<img>tag with the data URI insrc. - css background image: a CSS rule using
background-image: url(data:...). - html favicon: a
<link rel="icon">tag for an inline favicon. - html hyperlink: an
<a>link that downloads or opens the embedded file. - html iframe: an
<iframe>that renders the content inline. - javascript image: JavaScript that creates an
Imageobject. - javascript popup: JavaScript that opens the content in a new window.
- json: a JSON object with the file name, MIME type and data.
- xml: an XML element with the data inside a CDATA section.
Is it safe and how large will the result be?
Your file is never uploaded: it is read and converted locally by your browser using the File API, so even confidential documents stay on your device.
Base64 represents every 3 bytes with 4 characters, so the encoded result is about 33% larger than the original file (plus a few bytes for padding and the data URI prefix).
Frequently asked questions
How do I convert BMP to Base64?
Select your .bmp file above and click "Encode BMP to Base64". The converter reads the file in your browser and outputs the Base64 string or a ready data URI.
What does a Base64-encoded BMP start with?
A BMP file encoded to Base64 typically starts with "Qk". As a data URI it begins with "data:image/bmp;base64,".
Is there a file size limit?
There is no hard limit because the conversion runs locally, but very large files produce very long strings. Files up to about 50 MB work comfortably in modern browsers.
How do I convert the Base64 back to BMP?
Use the Base64 to BMP decoder: paste the string, and you can preview and download the original .bmp file.
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