KDP says the margin is too small
Amazon wants more room toward the glue when the book is thick. Word does not calculate that. Path A and B do, from real pages and paper.
If KDP sends the interior back with “margin is too small,” it is almost never that your type is large. It is the inside margin, the gutter, the one that tucks into the glue. On a thin book you barely notice. On a thick paperback, if type starts against the spine, part of the words vanish in the curve. Amazon publishes minima that rise with page count: about 0.375 inches up to 150 pages, 0.5 up to 300, 0.625 up to 500, 0.75 up to 700, and 0.875 above that. That is in their help on trim, bleed, and margins — not a forum trick.
Ingram, for its part, recommends about 0.5 inches (13 mm) of safety on all sides. A Word file with “mirror margins” of 2 cm sometimes passes on a slim book and fails at 400 pages. That is why I do not fight Word sections. On Path A or B I pick trim and paper, generate the preview, and the site takes the stricter of Amazon’s minimum for that count and Ingram’s, plus a little reading comfort, plus extra if the stock is thick or colour (coated and premium album papers get more gutter in our math).
The page count that matters is the final PDF, not “Word says 218.” The contents list, full-page images, chapters pushed to an odd page, and signature close all change the total. So the margin is calculated after layout, not before. If Amazon still complains, first check you did not upload the watermarked sample or a trim that differs from the title form. Second: generate again on Path A or B with the full manuscript and the right paper.
If the design was already paginated in Canva and type starts too close to the edge, Path B re-frames to the mold; do not widen margins by painting a white box over the art. And do not drop the body to 9 point “so it fits”: Amazon’s error is margin, not a long paragraph.
When the interior already closes, the Path D jacket uses that same count. A well-calculated gutter and a guessed spine are two different problems; here they come from the same spec sheet.
