Why spine width depends on page count and paper
The spine is the thickness of the book block, so it grows with the number of pages and with the thickness of the paper. White, cream, standard colour and premium colour papers are different thicknesses, and each printer publishes its own figures. KDP, IngramSpark and Lulu each calculate spines differently, and IngramSpark paperbacks use Ingram's own spine-width table for each paper type.
That is why one "universal" cover file stretched across every printer often fails a printer's checks. A cover that is correct for KDP can be a fraction of an inch off for IngramSpark.
How BookCovers.pro calculates the spine
- Enter the book details. Choose a trim size (seven are built in: 5×8, 5.5×8.5, 6×9, 6.14×9.21, 7×10, 8.5×8.5 and 8.5×11), your final page count and your paper stock (black and white on white, black and white on cream, standard colour or premium colour).
- Templates are generated for each printer. BookCovers.pro sizes a separate template for KDP, IngramSpark and Lulu, each with that printer's spine width, bleed and safety zones. The templates update as soon as you change the specs.
- Add the artwork. Upload a front cover you already have (PNG, JPG or WebP), or create one with AI. Three AI concepts per cover are free.
- Check each proof. The proof shows the front, spine, back, bleed and safety guides for each printer before you pay.
- Download. One credit downloads the whole bundle.
If your page count changes after you start, open "Book info" (Step 0), change it, and the print templates are regenerated. Re-proof the cover before downloading.
What one credit downloads
- A print-ready wrap PDF for KDP and one for IngramSpark, plus one for Lulu when the book has 32 pages or more (Lulu's own minimum)
- Optional hardcover case-laminate PDFs for KDP and IngramSpark (both printers require at least 76 pages for hardcover)
- A matching ebook cover JPEG
- A square 3000×3000 audiobook cover
Print covers are delivered as high-resolution RGB PDFs and 300 dpi PNGs at the exact full-wrap size. A clear area about 2 inches wide and 1.2 inches tall is kept in the lower-right corner of the back cover for the ISBN barcode, which KDP and IngramSpark add themselves.
Prices
- 1 cover: $24
- 5 covers: $99 ($19.80 each)
- 10 covers: $179 ($17.90 each)
- 25 covers: $379
- 50 covers: $629
- 100 covers: $1,129 ($11.29 each)
Credit packs are one-time purchases that never auto-renew, and credits are valid for two years. A free account is needed to save projects; designing, previewing and generating the templates cost nothing.
The printers' own calculators
Amazon KDP's Print Cover Calculator gives the exact dimensions of a cover and a downloadable template (PDF and PNG) to use as a guide layer in your own image editor, and IngramSpark offers a cover template generator to its publishers. They are the authority on each printer's numbers, and they are the right choice if you want to lay out the cover yourself in design software.
BookCovers.pro does the layout step as well: it places your artwork, spine text and back-cover copy onto each printer's dimensions, so you do not rebuild the back and spine by hand for every printer.
Current limits
Hardcover dust jackets with flaps and Lulu hardcovers are not supported yet. Because printer requirements can change, BookCovers.pro cannot guarantee that every file passes every printer's preflight, so check your specs against the printer's current requirements before you submit.
For cheaper ways to get a cover made at all, see cheap alternatives to hiring a book cover designer.
