Print format and platforms
KDP, IngramSpark, Barnes & Noble and Lulu — trims, gutters, spine calipers, barcode rules, hardcover, and what "approximate" means on a spine figure.
Manuscript Studio knows the print rules of four platforms. You pick one as your book's primary, and you can check the same book against others on the release board.
| Platform | Barcode | Spine figures |
|---|---|---|
| KDP | Prints its own — keep the zone clear | Published, exact for paperback |
| IngramSpark | You supply your own | Best-sourced, marked approximate |
| Barnes & Noble | Prints its own | Best-sourced, marked approximate |
| Lulu | Prints its own | Published formula, exact |
Switching platform re-checks everything: the trim list, the page range, the gutter table, the spine caliper and the barcode rule.
Trim size
Each platform prints a specific set of trims, and the set differs by binding — a platform may offer fourteen paperback sizes and five in hardcover.
The trim picker shows only what your platform and binding actually print. Switch to a platform that does not offer your size and it snaps to 6×9, which everybody prints.
Margins and the gutter
The inside margin — the gutter — must grow with the page count, because a thick book does not open flat. Every platform publishes a table for this.
Margins here are mirrored: the gutter is on the left of a right-hand page and the right of a left-hand page, so it always follows the binding. Margin presets are an outside edge plus a pad added to the platform's gutter rule, so the inside margin genuinely grows with the spine rather than being a flat number that stops being enough at 600 pages.
Hardcover is not a fat paperback
The boards overhang the trim, so the wrap is much larger, and there is a hinge either side of the spine where the case folds. Text placed in the hinge creases.
The board warns about it, and the page ranges for hardcover are quite different — typically a much higher minimum.
Spine width, and "approximate"
Spine width is page count times paper caliper. A caliper wrong by ten percent is a rejected cover.
Published third-party "spine calculators" disagree with the platforms' own help pages and with each other — in one case by nearly a tenth of an inch across 300 pages, which is enough to fail a cover.
So every figure carries its source and the date it was checked, and one of three confidence levels:
- Published — the platform states it openly. KDP paperback and Lulu.
- Derived — arithmetic on a figure the platform publishes.
- Approximate — best-sourced but not authoritative.
Where the figure is approximate, the app says so and asks you to read one number off the platform's own calculator. Your confirmed number always outranks anything computed.
Most hardcover formulas are kept inside the platforms' own calculators and are not published at all. Lulu's is the exception.
Interior bleed
Bleed grows the page asymmetrically — wider and taller, but never on the bound edge, which cannot bleed. Setting it symmetrically would shift the whole text block toward the gutter.
It also raises the platform's minimum outside margin.
What to watch for
- Set the platform before you design the cover. The spine caliper and the barcode rule both change with it, and the wrap geometry changes with them.
- On IngramSpark you must place your own ISBN barcode. The canvas labels the zone as yours rather than reserving it.
- Below roughly 80 pages there is no spine text, on any platform. The renderer drops it rather than printing something a trimmer will cut through.