KDP sells your printed book on Amazon. IngramSpark prints the same book for bookshops and libraries, which order through Ingram's catalogue. Switch on IngramSpark too in a paperback's or hardcover's settings, and the studio makes its files fit both.
- The last page is blank. IngramSpark prints its own barcode and print line on the last page, so the interior gets one or two more pages at the end when it needs them. KDP takes the same file. If those pages take the book past one of KDP's limits, the build's check says so.
- Binding and paper. A paperback is a paperback at IngramSpark too. A hardcover is a printed hardcover (a case laminate), or a printed hardcover with a dust jacket over it: IngramSpark prints the case and the jacket from a cover file each. Black-and-white books print on creme or white 50 lb paper, or on groundwood 38 lb (the US and the UK only); not every trim comes on every paper, and the settings say which do.
- The cover's size. IngramSpark's covers have their own sizes: a paperback's wrap with 1/8 inch of bleed, a printed hardcover's 5/8 inch wrap around its boards, or a dust jacket with 3 1/4 inch flaps. The settings show the size for your page count. The spine is an estimate from the page count and paper until you type in the spine width from IngramSpark's own cover template. The template is made for the book as it is: when its page count, paper or binding changes, the studio estimates the spine again until you enter the new template's width.
- In the cover editor. Switch the editor from KDP to IngramSpark: it lays the cover out at IngramSpark's sizes, with its safe areas and its 1.75 × 1 inch barcode space, and saves it beside the KDP cover. A hardcover with a dust jacket takes two files there, the printed case and the jacket: the jacket's flaps take the cover's colour and two texts of their own, a few lines about the book and a few about you. The editor's covers are RGB PDFs, as KDP takes them: IngramSpark recommends CMYK PDF/X-1a and converts RGB covers to CMYK itself before printing, so colours can shift a little. Its eproof shows how they print.
- What stops it. A trim or paper IngramSpark doesn't offer, a page count outside its limits, KDP's free ISBN (it works only at KDP), or KDP's Expanded Distribution: through it, KDP already lists the paperback with Ingram, and IngramSpark refuses a number that's listed there. IngramSpark needs an ISBN of your own, the same one KDP prints. Its own free ISBN, for US publishers, names Indy Pub as the publisher and works only at IngramSpark, so the book couldn't go to KDP under that number.
The studio never uploads anything: you upload the files to IngramSpark yourself. Order a printed proof from IngramSpark before you approve the book.