The selling column
Readers flip to the back for one reason: to decide. Lead with the blurb — hook, protagonist or problem, conflict, stakes — set in a type size that reads at arm's length, usually with clear paragraph breaks. Below or beside it, an author bio of two or three sentences and a small photo can add trust, and one or two strong review quotes can carry social proof. Resist filling every space: white space is what makes the column readable.
The production zone
The lower right of a KDP back cover belongs to the barcode: a roughly 2 × 1.2 inch area that must stay clear of essential content. KDP prints a barcode there automatically if your file does not include one, covering whatever sits underneath. A price is optional on self-published covers — the retail price lives on the store page — and if you add your own barcode it should sit on a light background inside the reserved zone.
Design continuity without competition
The back is part of the same wrap, so it continues the front's atmosphere — palette, type family, a secondary motif — while dropping the visual intensity. A busy back panel fights its own copy. Extend a texture, gradient, or quiet region of the artwork rather than mirroring the front image, and never run critical elements across the spine fold, where binding variance lives.
Hardcover backs and other formats
A KDP case-laminate hardcover back works the same way, with the barcode zone in the same corner, but jacket flaps do not exist — flap-style bio content moves onto the back panel or inside the book. Audiobook and ebook editions have no back cover at all; their retail description does the blurb's job, which is why the same positioning should be written once and adapted per context.
Sources: Amazon KDP cover preparation. Reviewed ; recheck the official page before production.