Authors may not realize that file size matters. If you don’t use Kindle Create or upload a compressed file (I prefer to upload pdf with bleed). You may be charged outrageous delivery fees which cut into profit. On average I’m charged between $0.10 to $0.25 per book because my files usually are under a MB. My suggestion when formatting ebooks is to be smart on photo usage. And what you add to your book regard to chapter names, in chapter breaks etc. Bookthreads