Calibre File Type Management (Kindle formatted Epub)

[gldnbrwncouches]

I've recently been getting books I purchase delivered through a service called Bookfunnel. They offer downloading a book in multiple formats if available for that book. Among the standard formats (epub, mobi, kepub, pdf, etc) there's also an option to download a "Kindle Epub file".

The kepub file downloads as "<bookname>.kepub.epub". In my experience, leaving it in this dual-extension style filename format will only show up as an "epub" in Calibre and it only stores one of each format per book. So I remove the ".epub" at the end and import it into Calibre as a ".kepub" file for the book, which allows for storing both the kepub and epub files and it works as expected when transferring it to my Kobo devices.

Similarly, the "Kindle Epub file" looks like "<bookname>.kindle.epub". I've been doing the same thing as the kepub so it ends up getting stored as a ".kindle" extension file for the book in Calibre. However, this means there's no real way for Calibre to interpret using it since ".kindle" isn't a real ebook format, but I keep it just in case it actually has better formatting structure for Kindle readers. Ideally, if it is actually better than the regular epub for kindle readers, this is the file I'd want to use for syncing over usb or sending to kindle via email, now that epub is actually supported there.

Two questions about this:

1. Is there a better way to import or store these so that I could more easily use them with Calibre and a Kindle device?

2. Does anyone whose seen these ".kindle.epub" files know if they carry any meaningful difference in formatting or structure than the regular epub files?

[JSWolf]

KePub is nothing to do with a Kindle. It's a Kobo ePub file. There are two programs on a Kobo for rendering ePub or KePub.

[gldnbrwncouches]

Originally Posted by JSWolf

KePub is nothing to do with a Kindle. It's a Kobo ePub file. There are two programs on a Kobo for rendering ePub or KePub.

Yes, I'm aware of that. Perhaps my previous post was unclear, but I was comparing the two download options the site gives. They are both epub files in the end. The ".kepub.epub" file is just an epub with the Kobo extra span tags and such for tracking reading progress and rendering better/faster on kobo devices. ".kepub" is a recognized extension in Calibre and I can transfer to my Kobo devices because it's recognized as such.

Contrast that with their "Kindle Epub file" download option that downloads another epub file, but with the ".kindle.epub" extension. If I do the same filename modification, I end up with a ".kindle" file that is an epub inside, but programs like Calibre that interpret based on file extension won't know what to with that since ".kindle" isn't really a recognized ebook extension like mobi, epub, or even kepub.

Question 1 is how to store/use this in Calibre without overwriting the regular epub file since it's basically one extension type per book in my experience and even though it won't complain about storing a ".kindle" filename, it won't be able to do anything with it either.

Question 2 asks if anyone has seen this before and if they know if they are actually any different than the regular epub file in a meaningful way, maybe similar to how a kepub carries those extra tags and such for their readers, but in this case for a kindle? I'm not an expert on internal epub structure or formatting, but I can tell you it has a different md5sum than the regular epub file download option, so something is different, just unclear what and if it's worth keeping the extra file, or just using the regular epub when using "Send to Kindle" or loading via Calibre.

[DNSB]

Originally Posted by gldnbrwncouches

2. Does anyone whose seen these ".kindle.epub" files know if they carry any meaningful difference in formatting or structure than the regular epub files?

The structure is basically the same but the .kindle.epub will use media queries to allow proper sizing for images when using Send to Kindle and it's kin. You will see various images that have larger version that is used for KF8/azw3 and a smaller version intended for mobi. The media queries will specify the sizing for the images sizes and margins for KF8/azw3 in percentages/em while those for mobi will specify these in pixels. The media queries will have multiple versions such as:

@media amzn-mobi {

@media not amzn-mobi {

@media amzn-kf8 {

@media amzn-mobi {
    div.title-page-title-subtitle-block {
        margin-bottom: 96px;
    }

@media not amzn-mobi {
    div.title-page-title-subtitle-block {
        margin-bottom: 3em;
    }

[gldnbrwncouches]

Awesome, so I guess that answers number 2. The file is at least minorly different in a way that's beneficial for Kindle readers.

Any idea on question 1? Is there a better way to store them so they're easier used by Calibre when I connect my Kindle or use Send to Kindle?

[DNSB]

For the friend of mine who has been downloading them to use with Send to Kindle, he just adds them to calibre and either converts to azw3 to sideload to their Kindle or sends to Amazon for them to convert and then sync to the Kindle. Amazon does not know or care about the .kindle.epub file extension. For the most part, their opinion has become that calibre does a better job of conversion than Amazon though they lose the ability to sync between their Kindle and their Kindle as they phrase it. Basically, one device makes the ability to sync reading progress a bit useless.