Why are my epub files so huge?

Report · Apr 10, 2017

I have just completed a very small epub ebook. It has three images (all jpegs, the largest 927kb, the other two under 100kb) and very little text. It all looks gorgeous, but I am having real problems with the file size. It ended up exporting to epub at 16MB, which is way too large. I have been saving as and I converted all the files to IDML and back again, but no dice, still 16MB. Assuming this was because of a lot of gunge collected as I put it together I began again, with all new paragraph styles etc just to be sure. Got it down to 6.7MB, which is still a ridiculous size for this ebook, but usable for my purposes. I am planning to make a much longer ebook (not image heavy, but a lot of text) and if the inflation continues at this rate I'll have 100MBs in no time for books that ought to be no more than 4MB. Why is thjs happening, and how can I make economical files?

Report · Apr 11, 2017

What version of InDesign? What version of EPUB? How many fonts are there and are they being embedded? Which fonts?

Report · Apr 11, 2017

Hi Bob, thanks for answering. It's the latest version, EPUB 3.0. Only one font (Georgia), though I'm using italics and bold. I'm unsure whether it's embedded - how do you tell?

I think I found out why the file swelled, though. I looked inside and found a rogue 5.6MB image that must have been generated during export (presumably the rasterized image?) I'm using a jpg as a cover image, that's the >1MB one. Is it possible to stop it generating this extra image and just use the one I put in? And - if you have time - what in general is best practice for slim EPUBs? Would deeply appreciate any advice.

Report · Apr 12, 2017

Use a very simple cover image or don't use one at all. You don't have to allow InDesign to generate one.

I don't recall ever trying to get a file down to the size you want/require. At a certain point you just can't go any smaller. The HTML and font files alone will cause the file to increase.

You still didn't tell us what version of InDesign you're using.

Report · Apr 13, 2017

Hi Bob, as I said (perhaps ambiguously) I'm using the latest version of InDesign. I'm not sure that you're talking about ebooks? Ftr, the average size for a 350p text book on Amazon is around 3.5MB. You don't want it too big because of download fees. I think I've solved my problem now, it seems to work fine if I tell it to use the jpg image for the cover instead of rasterising the image. Many thanks for your time.