Proofing a hardcover
A paperback proof teaches you about ink, paper and margins. A hardcover proof teaches you about construction.
The block of pages inside is the same file you already checked, and The proof checklist, front to back still applies to it. What is new is everything wrapped around that block. A hardcover case is built separately, wrapped, turned in and then married to the pages, and every one of those steps has a tolerance a glued paperback never has.
The case, before you open it
Put the book down closed and look at the object rather than the artwork.
- Is the wrap centered on the boards? The printed sheet is larger than the case and folds over every edge. If it went down slightly off, one board shows more turn-in than the other. Compare the fore edge of the front board with the fore edge of the back board, then the head with the tail.
- Are the corners turned cleanly? Look for puckering, a fold doubled back on itself, or a thin crescent of bare board showing at the point.
- Does the spine text sit between the hinges? Not centered in the spine width you typed into a field — centered in the strip you can see with the book closed. Look straight down the spine from above, the way a shelf presents it.
- Has the laminate lifted anywhere? Run a fingernail along the spine folds and around each corner. Bubbles, a silvery tunnel along a fold, or a lifted corner all show worst on dark covers.
The hinge is the fault nobody anticipates
A hardcover does not open at the spine edge. It opens at a hinge: a groove pressed into the case a short distance in from the spine fold, so the board pivots there instead of at the edge of the spine strip.
That groove eats artwork. The band of the front panel closest to the spine folds down into the crease, sits in shadow when the book is closed, and disappears from view when it is open. Series numbers, publisher marks, a keyline that hugs the spine fold, or a background element you expected to run continuously from spine to front are the usual casualties.
How far the hinge is set in depends on the printer and the board thickness, so do not carry a figure across from one company to another. Measure it on the proof in front of you, then hold that measurement against your file.
Whether it lies open, and how hard you had to push
Open the proof at six points and read the innermost words at each. The middle is the worst case. A case-bound book often lies flatter than a paperback of the same page count, which flatters a gutter that is genuinely too tight — so judge by whether you can read the words without pressing, not by whether the book stays open. If you are flattening it with a palm, the inside margin is short for the page count. Margins and gutters has the table.
If there is a jacket
A jacket is a separate object with its own failures, and none of them are visible in a PDF.
- Do the flaps fold where you designed? The fold should land on the panel boundary, not a few millimeters into your blurb or your author bio.
- Does the front panel's fold land on your fold line? The front panel begins at the flap fold, not at the trim edge of the book. Measure the white space left and right of your title on the visible face. If it was centered on the face rather than on the panel, the fold has moved it.
- Does the jacket slide? Tug it gently along the spine. It should sit snug and still move. One that grips will tear at a flap; one that slips drops down and shows a strip of bare case at the head.
- Check the case underneath. Take the jacket off. The plain case below it is part of the book, and nobody looks at it until the proof arrives.
In the Cover Maker. Set the binding and the printer and the wrap is rebuilt to that company's own case or jacket geometry — the differences between Amazon KDP, IngramSpark, Lulu and B&N Press are larger than most authors expect — with live trim, bleed and safe-area guides, and the spine computed from your real page count. Start a book → · about the Cover Maker
The spine arithmetic, checked in the hand
At KDP a hardcover spine is the paperback bulk plus 4.8 mm (0.188976 in). The case dominates a thin book: 120 pages of KDP white paper bulk to 0.270 inches, so the hardcover spine is about 0.459 inches — roughly 70 percent wider, from a page count that has not changed.
Lay a ruler across the closed spine and compare it with the number your cover was built for. If they disagree, the title that looked centered in your file is now closer to one hinge than the other. That is a rebuild, not a nudge.
The proof is also a range check
Page limits are tighter in hardcover. At KDP a hardcover runs 75 to 550 pages where a paperback runs 24 to 828, and other printers publish their own limits.
So a hardcover proof doubles as confirmation that the book is inside the range at all. A novella that makes a fine paperback may be too thin to bind, and a long book that prints happily in paperback can be over the ceiling — in which case the fix is volumes, not a cover. See Long books, page limits, and splitting into volumes.
Make yours
Everything here is built into the tools, and they are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: Checking a printed book for readability · More: Paperback, hardcover, dust jacket: what changes · Dust jackets, and the extra geometry they need · The proof checklist, front to back