BMP to CBZ Converter
FileFlip converts BMP to CBZ entirely inside your browser, using ImageMagick and MuPDF compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert a BMP file to CBZ?#
- Drop your BMP file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to CBZ and the conversion starts on its own. FileFlip downloads 24.1 MB of WebAssembly the first time and nothing after that, then runs ImageMagick and MuPDF on your own machine.
- Save the CBZ file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting BMP to CBZ lose quality?#
No. The BMP picture is placed into the CBZ document at its full resolution, so every pixel reaches it intact. What you give up is that it becomes a picture inside a document rather than text.
Is it safe to convert BMP files online?#
Yes, because nothing is uploaded. FileFlip converts BMP files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What BMP to CBZ actually does to the file#
Converting BMP to CBZ runs on ImageMagick and MuPDF, downloads 24.1 MB of WebAssembly the first time and nothing after that, places the picture into the document at full resolution.
| Engine | ImageMagick and MuPDF |
|---|---|
| Conversion path | 2 steps: BMP → PNG → CBZ |
| Downloaded to your browser | 24.1 MB, once, then cached by your browser |
| Quality | Pixels preserved |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
Worth knowing before you start:
- the picture is placed in the document as a picture; no text is recognised out of it
What is a BMP file?#
A BMP file holds a device-independent bitmap: a pixel grid stored with a Microsoft-defined header and, in the overwhelming majority of BMP files in the wild, no compression at all.
Use BMP when a Windows-native application, printer driver, or legacy tool specifically expects it, or when pixel data has to be stored with zero encoding overhead for a processing pipeline.
Convert BMP to PNG or JPEG for anything leaving that pipeline, since both produce a far smaller file and PNG matches BMP's lossless, generation-safe quality.
What is a CBZ file?#
A CBZ file is a ZIP archive of page images, usually JPEG or PNG, named so they sort into reading order, with nothing else defining it as a comic beyond that convention.
Use CBZ to distribute a scanned or digital comic as sequential page images that any comic reader opens without conversion.
Convert CBZ to PDF when a comic needs to move into software that expects a page-based document instead of a folder of images.
BMP to CBZ questions people ask#
Why are BMP files so much bigger than JPEG or PNG?
Most BMP files store every pixel's color value directly with no compression, so a BMP is close in size to the raw uncompressed image data. JPEG and PNG both apply compression, lossy in JPEG's case and lossless in PNG's, which is why the same photo saved as either is a fraction of the size of a BMP.
Can a BMP file be compressed?
Yes, though it's rare in practice. The BMP specification includes run-length encoding modes, RLE8 for 8-bit images and RLE4 for 4-bit images, that compress losslessly the same way GIF's LZW does, just less efficiently. Almost all BMP files encountered in practice still use BI_RGB, the uncompressed mode, because that is what most software defaults to writing.
Does BMP support transparency?
It can, but support is inconsistent. The BITMAPV4HEADER and BITMAPV5HEADER, both extensions to the original format, can store a 32-bit image with an alpha channel, but many image viewers, browsers, and older software ignore that alpha data entirely and render the image as fully opaque. PNG's alpha transparency is much more reliably supported across software.
Is BMP the same thing as a DIB?
They're closely related. DIB, device-independent bitmap, is the internal Windows data structure of header, color table, and pixel data that a BMP file wraps in a short file header. The .dib extension is used for that same data saved without expecting the .bmp file header, which is why BMP and DIB are treated as aliases of the same format.