Sudoku book generator for Amazon KDP

The one thing a sudoku book must get right

A sudoku with two valid solutions is broken: the solver who finds the other one checks the answer key, sees it disagree, and leaves a review saying the book is wrong. The reader can prove the fault from your own answer key. Removing clues without re-solving the grid after each removal is how such a puzzle gets made.

Puzzle Press starts from a full valid grid and digs clues out in symmetric pairs. Before each pair is removed, the grid is solved by a solver that counts solutions; if removing the pair would allow a second solution, the pair stays. Every puzzle in every book has exactly one answer, by construction. That check is what makes the hard and expert grades slower to make than the easy ones (measured below); the page shows progress while it works.

Grades

Clue layouts are rotationally symmetric: turn the grid upside down and the clues sit in the same squares. Grids are 9×9 with bold 3×3 boxes and numbering sized for a 6 × 9 page; large print sets 8.5 × 11 pages with 9×9 digits at about 38pt, puts one answer grid on each page so the solutions are large print too, and adds a "Large Print Edition" badge to the cover. For children's books there are 6×6 grids (2×3 boxes, clue bands 20/16/12/10) and 4×4 grids (2×2 boxes, 10/8/6/4) — and every small grid is verified to have one solution exactly as the 9×9 is.

Measured on 2,400 puzzles

On 21 October 2026 we ran the generator 200 times for every grade at every grid size and solved every result again from scratch. All 2,400 puzzles had exactly one solution, and every clue matched the answer key.

"Removals refused" counts the pairs of clues the generator tried to take out and had to put back, because without them the puzzle would have had a second solution. At easy that happens to about one try in seventeen; at expert, to nearly two in three. That is why expert is slow: each refusal costs a full solve.

Some finished grids cannot be dug down to 26 symmetric clues at all. The generator starts again from a new grid, up to 12 times per puzzle, and then keeps the closest it found. In this run 7 of the 200 expert puzzles came out one clue over target, at 27: the book gets a 27-clue puzzle that solves one way rather than a 26-clue one that doesn't. On 6×6, 8 expert puzzles of 200 stopped two clues over target, at 12; every other 6×6 and 4×4 grade hit its target every time, in under 40 ms each. Times are from Node on a desktop computer; a phone browser will be slower.

Solutions

Filled grids, 6 to a page at 6 × 9, each labelled with its puzzle number and grade, after a "Solutions" divider. Large enough to read; small enough that a 100-puzzle book stays at 124 pages.

What a book costs to print, and earns

Page count is title, copyright, one puzzle per page, a divider, solutions 6 to a page, and four notes pages, rounded to an even number. Printing is KDP's flat rate up to 110 pages, then $1.00 plus 1.2¢ a page. Royalty calculator for other prices and trims.

Sudoku books have no theme to choose, so the niche is in the audience: large print, travel size, "for beginners", "expert only", a volume number. See choosing a niche in the guide.

The rules every KDP interior has to meet

Page size equal to the trim, margins that grow with the page count, fonts embedded, 24 to 828 pages and an even count, a cover whose spine width is page count × paper thickness with nothing added. The tool lays every book out to these; if you would rather know them yourself, they are all in the guide, with the numbers.