Large Scrivener Mobi Files

Has anyone noticed the size of Scrivener-produced Mobi files? I used the book “How to Format Your Novel for Kindle, Nook, the iBookstore, Smashwords, and CreateSpace…in One Afternoon (for Mac)” by Ed Ditto to compile my first few ebooks using Scrivener on my new computer. Previously I used HTML templates and used Calibre to convert them, but that is no longer working for Epub. I’m hoping to use Scrivener as a one-stop shop for ebooks now.

Anyway, after the final compiles I found the following file sizes:

Epub: 144 kb
Mobi: 330 kb

It was a shock to see the file size difference, and this is with a short story 2-pack. I went back to short stories that were compiled the old way and the average for this size would have typically been be 105 - 140 kb using the HTML-to-Calibre method.

Just for kicks, I took the Epub version produced by Scrivener and used Calibre to convert it into Mobi. The resulting file is 165 kb.

For now I think that’s what I need to do. 330kb is about the size of a novel, not a short story 2-pack. Amazon charges for file size, so this bloat would cost me money. I can’t imagine what a Scrivener-generated novel would be using my current compile settings (based off the book). Ouch.

Are there any compile settings that could be causing this? And yes, I did rule out the size of the cover. That is not what is causing this.

Yup, that is expected behaviour at this point in time, and it has nothing to do with Scrivener and everything to do with KindleGen (you can verify that by checking the option to include source files in the KindleGen compile option pane, and then checking the size of that output folder after compiling, you’ll see that what Scrivener generates is closer to the real size of the e-book; zip that folder and it should be about the same as the ePub). Right now Amazon is transitioning their e-book format from the older MobiPocket format, to the new KF8 format. These two formats are not cross-compatible, they are as different from one another as Mobi is to ePub. Thus for books to be readable on every Kindle from gen 1 to the latest Fire HD, books need to have both the Mobi and KF8 versions embedded in a single “fatter” package.

Unfortunately, Amazon did not a design a very efficient system for this. Instead of sharing resources between each other, they duplicate the entire work. This isn’t too bad on books that are just a bunch of HTML files, but once illustrations are added, this can quickly bloat the size as each picture ends up being included twice. Once can speculate about that and Amazon’s large-book fee, but that’s another topic. :slight_smile:

So the short summary is: yes, that is expect and yes it is annoying, but you definitely don’t want to be making new books these days that are .mobi format only, and tools that create a .mobi file more in line with the ePub size (like Calibre) are going to be doing that instead of producing the double book package.

First off…thanks for using my book. A couple of things to consider if you haven’t:

  1. Have you tried comparing your post-compile file size on your local system to the post-upload file size at the KDP? If not, check the bottom of the royalties table in step eight of the KDP book creation process to see what your final book size is…i.e., what Amazon will be charging the delivery fee against. This may save you the extra conversion step you describe, since I expect this number to match the epub size much more closely.

For example, my formatting book compiles to 7 MB on my local system (lots of images), but ends up at 2.54 MB after KDP upload/conversion…which is, interestingly, smaller than its 4.4 MB epub size (again on my local system.) So at Amazon’s $0.15/MB delivery charge, I pay $0.38 on each book.

  1. I’m just now beginning to experiment with skipping the .mobi step and uploading epubs directly to the KDP to see how they turn out. I may very well eliminate the .mobi compilation step in future editions of the book, if I can prove to my own satisfaction that there are no significant differences in the KDP’s treatment of the two different upload formats.

Please, keep us updated whether this works or not!

Sure thing. My early experiments in the Kindle Previewer make it look like there’s no significant difference, but I really need to roll my sleeves up and dig into the differences in table support capability, because I suspect that’s where things will get hairy.

I’m still convinced that the best way to insert a table into an ebook is as an embedded image, though.

Interestingly, what the Kindle Previewer does when asked to open an epub is that it bumps Kindlegen on to convert the epub to mobi. So anyone who’s looking for a quick epub to mobi converter – quicker than calibre – I encourage you to try the Kindle Previewer.

Ed, I just uploaded a book since I first posted here. On Amazon, I uploaded the bulky Mobi file, checked the transmission fees, then uploaded an Epub and checked (I forgot to create a Mobi with Calibre to check that comparison). The transmission fees were the exact same for the novel, so it looks like Amazon does indeed convert them to around the same size.

Good news for me, as I don’t now have to use Calibre for a step in this process. I can go ahead and use Scrivener’s version without worrying that I’ll be paying more in transmission costs.

As for your second point, in the KDP previewer, the epub did look just fine. But, to be on the safe side, I reloaded the Mobi version and published with that. This was a book in my big series and I didn’t want to experiment with it. Not with so many readers waiting for it. Just in case I missed something. :stuck_out_tongue:

Thanks for that report. It is good to know that Amazon isn’t charging money for their own format transition burdens. I feel better recommending people stick with the bloated KindleGen since there are no consequences, and it will make the books better for the future.

Definitely; thanks for that report. Amazon’s transmission fees are ridiculous enough as it is without the file size being padded by the very compilation application they want you to use. That’d be like a dentist recommending that you eat sweets before bed every night.

Mrs Pigfender goes to Spin classes. When the Spin instructor was going away for 2 weeks on holiday he gave strict instructions that they should all eat whatever they want and try not to exercise while he was away (as he’d need the money when he gets back).