Contents | Start | End | Previous: KB0164: Why does Amazon KDP say that my ebook has an unrecognised file format? | Next: KB0166: How can I move the table of contents from the start of the book?
See also:
What do I do if my Kindle book is rejected by Amazon?
Why are Kindle files larger than Epub files?
How do I change image size in Jutoh?
You may find the Epub or Kindle file size is larger than you expected.
If you are looking at the .mobi file size in a file viewer, this does not indicate the deliverable size, since it also includes the Epub source. Normally the deliverable size is around half of the compiled .mobi file size. Jutoh will tell you the estimated deliverable size in the error window and status bar after compiling. This figure may still not match the file size reported by Amazon in 'Book details' on the book product page; it's not possible to know exactly what this file contains as Amazon isn't telling, and there may be device-specific manipulation of the file when delivering it.
Here are the things you can do to reduce the file size of your book.
Reduce the image quality, by setting a lower value for the configuration option Image quality. If your images are already in JPEG format, to make Jutoh reduce the quality you will need to set Convert images to JPEG to "All except GIF, recompressing JPEG".
Reduce the image resolution. To reduce the resolution within your Jutoh project - resulting in both a smaller project and smaller output files - click each image and then click Resample, entering a smaller pixel size. To reduce the resolution only in output files, set the configuration option Maximum image width to a pixel value such as 800. This will resample the images when they are written to the ebook, not permanently. To keep a specified image size in the displayed book regardless of the resolution, click on the image and set a width in the Size tab.
If you have a lot of identical images in your book, click on each one and set the Name to the same value. Also, check the configuration option Use specified image file names for all relevant configurations. Jutoh will now only write the first image of a set of images with the same name.
Check that some images aren't bigger than expected. Switch to an Epub configuration, compile the book, and use Book | Examine to look at the contents of the Epub file. Jutoh will show the image sizes. In particular you might have used a large cover image; you can use a small cover image (say, 600x800) because most distributors ask for a separate cover anyway. Amazon KDP ignores the image that's in your compiled book so you can discount that image's size.
If you are embedding a font, but only use a small number of characters in the font, you can create new 'subsetted' fonts that discard some of the glyphs that your book doesn't need. For example, try using Calibre's ebook-polish command after compilation to remove redundant characters from the font. You could put this command in the Post-compile command configuration option:
c:\Program Files (x86)\Calibre2\ebook-polish --subset-fonts %FOLDER%\%FILENAME%
See also Can Jutoh perform font subsetting?
Note that formatting and text don't take much space, so there's not much scope for optimization of these aspects.
To reduce the size of your Jutoh project file, use File | Compact Project now and again. This has no impact on your compiled books.
Keywords: optimise file, optimize file, shrink file, reduce file size, large file
Contents | Start | End | Previous: KB0164: Why does Amazon KDP say that my ebook has an unrecognised file format? | Next: KB0166: How can I move the table of contents from the start of the book?