I used Kindle Unpack in Calibre to unpack a .mobi file, so I could correct mistakes in images and text. It was easy - images were JPGs or JPEGs and text was .html or .htmlx files. Now I need to repack it all as a .mobi file and I'm stumped. The folders I have before me are now:

  • HDimages (empty folder)
  • mobi7
  • mobi8
  • mimetype
  • kindlegenbuild.log

(it looks like the the last 4 all go back into a kindlegenbuild.zip file.

I've looked for a plugin for Calibre that does it, but no luck.

3 Answers 3


KindleUnpack is primarily intended for debugging KindleGen issues. If your original Kindle books is an AZW3 book or a MOBI book generated with KindleGen, you can edit it with Calibre Editor.

Simply select the book in Calibre, right-click it and select Edit book. This will automatically unpack the book and open it in Calibre Editor. If you save the book it'll be automatically reassembled.


Keep in mind Calibre won’t help if it is a fixed layout book. While azw3 has all the data, it won’t correctly export to mobi. all bug reports regarding fixed layouts are turned down. I have an epub with lots of images, 10 mb in size, but the resulting mobi is 200 kb, it completely ignores all the images when it converts.

kindle preview generates a correct mobi for you from an epub, but it adds your sourcefiles into it. so that the resulting file is much bigger than necessary

It would be great with a mobi packer plugin for Calibre.

edit: kindlegen takes an undocumented parameter: -dont_append_source


To answer the original question, assuming the edits were made to the mobi8 files, just use an epub packager (like ePub Zip/Unzip) to convert the mobi8 folder to an epub file (I also delete the .epub version contained within the mobi8 first). Discard the rest. Then convert new 'mobi8.epub' file to .mobi using Kindlegen (or the Kindle previewer).

Don't use Calibre for fixed ebooks, as was mentioned in the past post. If you just have some minor edits, unpacking it to edit and then repackaging it as an epub is probably the cleanest way to go.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.