The book barcode, explained: ISBN, EAN-13, and the price add-on
What the barcode is actually encoding
Every printed book with an ISBN carries that number twice: once as human-readable digits, and once as a scannable EAN-13 barcode. The barcode is not a separate identifier, it is a machine-readable version of the same ISBN that already sits on your copyright page and your cover. That is the whole function of the main barcode: convert the ISBN into stripes a bookstore or library scanner can read at the register.
Because it encodes the ISBN specifically, every format of your book needs its own barcode to go with its own ISBN. A paperback, a hardcover, and a wide-distribution eBook are each a distinct edition and, per standard ISBN practice, each needs its own ISBN and therefore its own barcode artwork.
The price add-on: what that little extra strip is for
Look closely at many book barcodes and you will notice a shorter five-digit barcode sitting just to the right of the main one. That is an optional add-on symbol, and its job is to encode the book's list price so a retailer's scanner can pull it up alongside the ISBN. Publishers who do not want a fixed price baked into their cover artwork, which is common for self-published authors who may adjust pricing over a book's life, use the placeholder digits 90000 in that add-on. Those digits signal that no price is encoded, and the retailer's own system supplies the current price instead.
This is one of the more misunderstood parts of a book's back cover. Authors sometimes assume the add-on is decorative or mandatory. It is neither: it is optional, and most free barcode generators default to the no-price placeholder unless you tell them otherwise.
KDP versus IngramSpark: two different approaches
| Printer | Barcode requirement |
|---|---|
| Amazon KDP | Optional in your file. Leave the designated space open and KDP places its own barcode automatically at no charge. |
| IngramSpark | Mandatory, built into the cover file, 100% black on a white background. If not supplying one, the specifications call for leaving a clear 1.75 by 1 inch box for it. |
This difference trips up a lot of authors who publish the same title on both platforms with a single cover file. A cover built for KDP, with an empty barcode area and no black box specified, can fail IngramSpark's review because IngramSpark expects the barcode present and printed correctly, not merely blank space assumed to be filled later. Each printer's cover file needs to be built to that printer's own barcode rule, not reused wholesale.
The black box problem
IngramSpark's insistence on 100% black is not a style preference, it is a scanning requirement. A barcode printed in rich black, the CMYK mix many designers use for deep, richer-looking black elsewhere on a cover, can scan poorly or fail entirely because the ink layering is inconsistent at that resolution. The barcode and its background need pure black text on pure white, no registration black, no screened tint, no color mixed in for depth. This single detail, easy to miss if you are applying one "rich black" swatch across an entire cover design, is a common and entirely avoidable rejection cause.
Do you need to buy a barcode?
Not usually. Bowker, the main US ISBN agency, sells the ISBNs themselves, either as a single ISBN or as a ten-pack for authors planning multiple formats or titles. Once you own the ISBN, free barcode generators can turn that number into print-ready EAN-13 artwork, and both KDP and IngramSpark accept barcodes produced this way as long as the image meets their black-and-white and placement rules. Paying separately for a barcode image on top of the ISBN itself is rarely necessary.
The one caveat: KDP's free ISBN option is valid only on Amazon, and a book published under it cannot be used at IngramSpark. If you plan to go wide, budget for your own ISBN from the start rather than discovering the limitation after your cover is already built.
Where the barcode sits on the cover
Placement matters as much as content. The barcode traditionally sits in the lower third of the back cover, clear of any text, folds, or design elements, inside the box size each printer specifies. Because IngramSpark's specifications describe a 1.75 by 1 inch clear space when you are not supplying your own barcode, that is a reasonable working footprint to reserve on a back cover layout even if you plan to add your own artwork, so nothing else on the page crowds the eventual barcode position.
The practical checklist
- Confirm you have the correct ISBN for this specific format before generating any barcode.
- Decide whether you want the price add-on encoded, or use the 90000 no-price placeholder.
- For KDP, either leave the space open for their free auto-placement or supply your own correctly sized barcode.
- For IngramSpark, build the barcode into the file yourself, in pure black on pure white, not rich black.
- Build a separate cover file per printer rather than assuming one barcode setup works everywhere.
Every BookDesignerAI cover set, whether for KDP, IngramSpark, or Lulu, includes a correctly placed EAN-13 barcode built to that printer's own specification, generated as part of the full print wrap Cantos, our book-design AI, produces alongside your interior and eBook files. Start with proof: upload your manuscript and get a free professionally typeset proof copy of your whole book. No credit card, and nothing is ever trained on your work.
Get the Free PreviewSources: Amazon KDP's published cover specifications; IngramSpark File Creation Guide (5.11.26); Bowker ISBN pricing. Related: ISBN guide for self-publishers · IngramSpark cover rejections, decoded · KDP cover rejections, decoded
Frequently asked questions
What does the barcode on the back of a book actually encode?
The main EAN-13 barcode encodes your book's ISBN, the same thirteen digit number printed above or below it. An optional five-digit add-on barcode alongside it can encode your list price; publishers who do not want the price locked into the artwork use the placeholder 90000, which means no price is encoded.
Do I need to buy a barcode separately from my ISBN?
Usually not. Free barcode generators can turn any ISBN into a print-ready EAN-13 image, and both KDP and IngramSpark work with barcodes generated this way. Bowker, the main US ISBN agency, sells ISBNs themselves (a single ISBN or a ten-pack), but a separate purchased barcode image is not something most authors need.
Does Amazon KDP require a barcode on my cover file?
No. If you leave the designated space open on your back cover, KDP places its own barcode automatically at no charge. You only need to supply your own barcode artwork if you want a specific placement or styling and are confident in the file's accuracy.
Why did IngramSpark reject my cover over the barcode?
IngramSpark requires the barcode to be built into your cover file, printed 100% black on a white background, not registration black or a screened tint. If you are not supplying one, IngramSpark's file specifications call for leaving a clear 1.75 by 1 inch box for it. Rich black or CMYK-mixed black in that box is a common rejection cause.