MOBI/AZW3 → CBZ/CBR

What is MOBI/AZW3?

Mobipocket (.mobi) was long the default format Amazon accepted for Kindle delivery. AZW3 (also called KF8) is its successor with fuller HTML5/CSS support, and .azw is an earlier Amazon container. All three reflow and carry navigation and metadata, so they behave as one family. They are proprietary to Amazon's ecosystem, and since 2022 Amazon sends KFX/EPUB instead, so .mobi is mostly a legacy format now.

What is CBZ/CBR?

A comic book archive is not a real format but a folder of images packed in order: .cbz is ZIP, .cbr is RAR, .cbt is TAR and .cb7 is 7z, renamed so readers recognise it. There is no text layer and no typography — each page is a single full-page image, and reading order comes from filename sorting (which is why unpadded names like 1.jpg, 2.jpg … 10.jpg put page 10 right after page 1).

What to watch out for when converting MOBI/AZW3 to CBZ/CBR

Extracting from the source

.mobi/.azw3 are proprietary Amazon binary containers with no official parsing spec; third-party tools rely on reverse engineering and occasionally fail or drop metadata. AZW3 stores HTML internally, so extracting text is easier than preserving layout.

Writing the target format

Converting to a comic archive really just packs images under ordered names; all text is discarded. Zero-pad the filenames (001.jpg, 002.jpg) so sorting works, and note that .cbr needs RAR tools while most readers handle .cbz (ZIP) best.

Where the two formats interact

• Reflow is lost: the target freezes the layout, so readers can no longer change font size or line width. Long novels become zoom-and-pan on small screens — the most common reason a conversion ends up harder to read. Unless you need print or layout-critical delivery, keep a reflowable copy for reading.
• The target is image-only: all text in the source is discarded (or survives only as pixels). If your goal is content that can be searched, copied or read aloud, this direction is wrong — pick a text-preserving target instead.
• The source carries real navigation while the target has no concept of chapters, so reading becomes one long scroll. If navigation still matters, keep explicit, uniformly formatted chapter heading lines in the output.
• The source is a proprietary binary container and the target is an archive with a mandated directory structure. This is not unpack-and-repack: a real parse and rebuild must happen in between, so use a mature tool — hand-rolling it almost always yields a file no reader accepts.

Post-conversion checklist

1. Convert the first three chapters as a trial and check for lost text, interleaved lines or misplaced blocks before doing the whole book.
2. Confirm illustration count and placement — check that images are not all dumped at the end of a chapter.
3. Fill in title, author and language — a wrong language tag breaks typesetting such as Chinese line breaking.

Converting novels: what is different

Fiction is the most common and the most peculiar kind of e-book: hundreds or thousands of chapters, almost no figures, often nothing but a TXT source, and Chinese sources that frequently carry anti-piracy garbling. These are the points that bite hardest.

• The target has no notion of a table of contents, and not being able to jump to a chapter is the worst part of reading something long. If you will keep reading it, keep a navigable copy as well (EPUB or Kindle) and treat this one as the distribution or archive copy.
• Once a long novel is in a fixed layout, reading on a phone means zooming and panning. Fiction is the worst fit for fixed layout of any genre: almost no figures, all continuous text. Unless you are printing or submitting it, prefer a reflowable format for novels.
• Volume markers ("Volume One", "Volume Two") usually degrade to ordinary headings, losing the volume/chapter hierarchy. If that matters, promote volume headings one level in an editor afterwards so they are not siblings of chapter titles.

Tools for converting MOBI/AZW3 to CBZ/CBR

Any of the tools below can handle this direction; pick one by your operating system and how many files you have. Read the previous section first — doing the steps out of order (converting a scanned file before running OCR, for instance) usually means starting over.

Common questions

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