Every KDP paperback carries an ISBN barcode on its back cover. You can add your own or leave the space for KDP. Either way, the corner it goes in has to be planned before the cover is finished.
If you add no barcode
KDP places one on the back cover for you, at no cost. Its help pages put it in a 2 × 1.2 inch white box in the lower right-hand corner. A cover with images or text where the barcode goes is rejected, so that corner has to stay empty.
KDP does not publish the exact position. A safe reading uses its own figures: the suggested size of 2 × 1.2 inches, at least 0.25″ from the trim. That is an empty area of 2.25 × 1.45 inches, measured from the bottom and outside edges of the back cover.
If you add your own
A barcode of your own has to meet all of these:
- Size: 2 × 1.2 inches suggested, 1.4 × 0.8 inches at least.
- Position: at least 0.25″ from the spine and the trim, right side up and square to the cover.
- Background: solid white.
- Color: 100% black, not RGB or CMYK color and not registration black.
- File: its own image, not flattened into the cover picture. Vector is preferred; a pixel image needs 300 PPI.
- Sharpness: sharp and clear, not blurred or pixelated.
- ISBN: valid, and exactly the book's own ISBN. A price code, if there is one, matches the list price.
A QR code or a UPC barcode may also go on the cover, but not in the space kept for the ISBN barcode. KDP does not support two-stage barcodes, which are used for Japanese books.
If your barcode fails KDP's checks, KDP advises removing it and letting Amazon place one, at no extra cost.
Which to choose
Leaving the space to KDP is the simpler choice. The barcode always carries the right ISBN, and it costs nothing. A barcode of your own is worth the work only if you need something it gives you, such as a price code.
Transparency codes, which some KDP barcodes used to carry, are being retired. They are not available for books created after November 2025.
What Torcul does
Torcul draws no barcode, so every cover it makes gets KDP's. It keeps the 2.25 × 1.45 inch corner of the back cover empty, then reads the finished cover file for anything printed there. A full cover uploaded from a designer is used as it is, and Torcul says where KDP prints the barcode and that the area must stay empty.
Sources
None of this guarantees that KDP will accept a cover. KDP changes its help pages, so check the date on this one and on any report a tool gives you.