Ebook file size??! 1138MB

[Lesi]

Hi,

Why are ebook file sizes a) so huge, and b) so different from each other?

I have a novel on my Kindle that is 1138MB. Some others are around 200MB. Many of my other books are around 200KB. Why the size discrepancy, and can I make them smaller somehow, without losing quality? I was told I would get 1000s of books on this Kindle Paperwhite Signature (32GB), but I have put 180 books on there and almost 10GB is used already.

The files were mostly epub and I converted to MOBI automatically in Calibre when I sent to device. They were close to the same size before the conversion to MOBI so I do not think the conversion is the issue.

In a couple of cases the huge files were textbooks (which I deleted) but the large files that remain are fairly regular books.

tks

[pdurrant]

Originally Posted by Lesi

Why are ebook file sizes a) so huge, and b) so different from each other?

Almost always the answer is images. Very rarely, the formatting of the text may be so swollen by unnecessary markup that it affects the size.

ePubs are just zip files by another name, so you can unzip a renamed copy and find out what's making the book files so big.

For example, the most recently bought book I have is Dean Koontz's The Bad Weather Friend. A novel of around 330 pages in paperback. The AZW3 download from Amazon is 1.1MB, the converted ePub is 933KB. Expanding the ePub gives a 1.6MB folder, of which 733KB is text, 556 KB is images, 188KB is fonts and 122KB is the cover image.


You can examine your books similarly.

[ownedbycats]

Originally Posted by pdurrant

Almost always the answer is images.

Calibre's 'Polish books' has an option to losslessly compress images. This may help if the book was published with badly-optimized images.

[JSWolf]

Originally Posted by ownedbycats

Calibre's 'Polish books' has an option to losslessly compress images. This may help if the book was published with badly-optimized images.

That is a good idea to make the eBooks smaller.

[JSWolf]

eBooks from Penguin Random House have a next reads HTML It uses a graphic image and 2 or 3 embedded fonts. None of this is needed and can all be removed.

Also, embedded fonts can make eBooks larger. You can use Polish Books to subset the fonts so they are smaller.

[fogice]

Originally Posted by ownedbycats

Calibre's 'Polish books' has an option to losslessly compress images. This may help if the book was published with badly-optimized images.

You can also do lossy compression if you want more space reduction. Hit the 'Edit Book' button, go to 'Tools > Compress Images Losslessly' (sic), and in the dialog box select 'Enable lossy compression of JPEG images'.

Originally Posted by JSWolf

Also, embedded fonts can make eBooks larger. You can use Polish Books to subset the fonts so they are smaller.

And if you don't care about the fonts at all, hit the 'Convert Books' button, go to 'Look & feel > Styling', select the Fonts box, and the conversion will remove all fonts and CSS references to those fonts.

[JSWolf]

Originally Posted by fogice

You can also do lossy compression if you want more space reduction. Hit the 'Edit Book' button, go to 'Tools > Compress Images Losslessly' (sic), and in the dialog box select 'Enable lossy compression of JPEG images'.

And if you don't care about the fonts at all, hit the 'Convert Books' button, go to 'Look & feel > Styling', select the Fonts box, and the conversion will remove all fonts and CSS references to those fonts.

Unless you know what fonts are embedded, you don't know which fonts you want or not. For example, an italic font can be embedded and used. But if you remove the font, you lose the italics as there is no CSS code to to make the current font italics. So you have to be careful about willy nilly removing fonts.

[theducks]

HiRes Photo quality images when the details (eg Maps) are not needed.
Ads that show full size covers for multiple books (hopefully just the Authors work and not the publishers stable)

Common fonts (those that are already on many devices.) A holdover from the early days?

bloatware (added stuff that does not benefit just YOU. eg Trackers for ads)

[nabsltd]

Originally Posted by Lesi

I have a novel on my Kindle that is 1138MB. Some others are around 200MB.

Files this large are almost certainly a book where every page is an image.

If the first example is a 500 page novel, then each page uses 2.276MB (on average). This is large enough to hold a 3000x4000 pixel JPEG. Even the 200MB book would allow 500 pages of 1000x1600 pixel JPEGs.