Hardcover on KDP, formatted and certified
Five allowed trims. A page-count floor most paperback formatters never check. A spine width that has to be exactly right, or the wrap doesn't fit. We calculate all of it, then verify it against KDP's hardcover rulebook.
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The 5 trims KDP allows for hardcover
Paperback on KDP accepts any custom trim from 4″×6″ to 8.5″×11.69″. Hardcover doesn't work that way. Amazon offers exactly five sizes, full stop:
| Trim | Notes |
|---|---|
| 5.5″ × 8.5″ | Smallest hardcover trim; roomy fiction / short nonfiction |
| 6″ × 9″ | The standard nonfiction and general trade size |
| 6.14″ × 9.21″ | UK royal format |
| 7″ × 10″ | Workbooks, manuals, large-print hardcover editions |
| 8.25″ × 11″ | Largest KDP hardcover trim |
Design a cover for a size outside this list and KDP simply won't offer hardcover at checkout. There's no error message pointing at the cause, just a missing option. It's the single most common way self-publishers discover, late, that their hardcover plan doesn't work.
The page-count floor is the other trap: hardcover needs at least 75 pages of block to hold its case, well above paperback's 24-page floor. A slim book that works fine in paperback can be turned away from hardcover entirely.
Spine width and the cover wrap
A hardcover cover isn't a flat rectangle. It's a wrap around two binder boards and a spine, and the spine width has to match your exact page count and paper stock, or the cover physically won't fit the printed block. Typesheep calculates it per build:
- Spine width: roughly 0.002252″ per page on white paper, 0.0025″ per page on cream, plus a board allowance for the two binder boards and crash lining.
- Case-wrap bleed: a 15mm wrap allowance around the full cover.
- Text safe zone: 16mm minimum clearance for any text or logo, so nothing gets folded into the hinge.
- Spine-safe margin: spine text kept clear of the fold on both sides.
Every certified build includes a cover template PDF with this math already applied. The spine panel is sized to your book's actual final page count, not an estimate from your manuscript's draft length.
Add hardcover without starting over
If your paperback was built through Typesheep, hardcover is a $20 additional edition on the same title: same source file, same certificate discipline, a new build re-run against the hardcover-specific trim whitelist, page-count floor, and spine math above. It's not the paperback rules re-labeled.
Build hardcover standalone, or add it to a published title
- Hardcover print-interior PDF, one of the 5 KDP trims
- Cover template with exact spine width for your page count
- EPUB 3 for Kindle
- Preflight certificate: every KDP rule checked
- 30 days of unlimited rebuilds
- Refund if KDP rejects a certified file
Already published the paperback with us? Adding hardcover to the same title is $20.
What authors ask about hardcover on KDP
What trim sizes does KDP hardcover support?
Exactly five: 5.5×8.5, 6×9, 6.14×9.21, 7×10, and 8.25×11. Unlike paperback's open range, hardcover is a fixed whitelist.
How many pages does a KDP hardcover need?
75 to 550 pages, on white or cream paper. That's a much higher floor than paperback's 24 pages, because the binding needs enough block to hold its case.
How is spine width calculated for KDP hardcover?
Roughly 0.002252″ per page on white paper, 0.0025″ on cream, plus a board allowance for the binder boards and crash lining. Typesheep calculates it automatically and generates a matching cover template.
Can I use premium color paper with KDP hardcover?
No. Hardcover is only offered on white or cream paper. That restriction comes from KDP itself, so no formatter can lift it.
Can I add hardcover to a book I already published?
Yes. If the paperback was built through Typesheep, adding hardcover to the same title is a $20 additional edition.