Retail price per book - Fixed fee per book to produce the book - Per page charge based on number of pages in book - Percentage paid to distribution channel = Royalty paid to author (toughnickel.com)
Please note that for print book you should design your final cover only after your interior file is finally formatted so that you know the right page size and exact number of pages in your book. (pothi.com)
When an individual subscriber reads a certain number of pages in your book for the first time (and only for the first time), you'll be paid a share of the KDP Select Global Fund. (selfpublishingrelief.com)