Sudoku Generator for KDP
Pick a size and a difficulty, get a print-ready puzzle page. Free, no account, no watermark — and the PDF is yours to publish and sell on Amazon KDP.
Built for publishers, not for worksheets
Most free sudoku makers are built for a player who wants one grid this afternoon. That is a real need, and it is a different need from yours. A worksheet gets photocopied; a KDP interior gets printed by Amazon at 300 DPI, bound with a gutter, and rejected outright if the type is too small or the content strays into the margin.
So the differences here are the ones that only matter if you are selling the result:
- Vector PDF, not a screenshot. The PDF is real page geometry — digits are text, lines are lines. Print it at any size and the numbers stay crisp.
- No watermark, no attribution line. Not on the free tier, not as a trial. A watermark on a page you intend to sell makes the tool useless for its actual purpose.
- Exactly one solution. Every grid is uniqueness- checked as clues are removed. A book that prints two valid fills for one puzzle earns the one-star review it deserves.
- The same rendering engine as the paid editor. The page you download comes out of the identical layout and rendering code that produces a full Book Studio interior.
How to use it
- Pick a board size. 9×9 is the classic that sudoku-book buyers expect. 4×4 and 6×6 suit children and large print. 16×16 is a super sudoku for enthusiasts.
- Pick a difficulty. This is how many given numbers stay on the grid, not a marketing label. Keep it consistent across a book — readers notice when puzzle 14 is dramatically easier than puzzle 13.
- Name the puzzle if you want a filename that is not the default. The printed page titles itself as a sudoku.
- Generate, then generate again. A second press gives a different unique grid at the same settings.
- Check the answer key. The tab above the preview renders the filled grid. It costs nothing extra.
- Download it. A two-page PDF, or a ZIP of both sheets as 300 DPI PNGs — whichever your layout tool wants.
Choosing a size and a difficulty
Size and difficulty are independent levers. A 4×4 Extreme is still a small board; a 9×9 Easy is still a full classic sudoku with more given numbers. These combinations print well and hold up across a whole book:
| Audience | Size | Difficulty |
|---|---|---|
| Children (5–8) | 4×4 | Very Easy or Easy |
| Children (9–12) | 6×6 | Easy or Medium |
| Large print / seniors | 6×6 or 9×9 | Easy |
| General adult | 9×9 | Medium |
| Enthusiast | 9×9 or 16×16 | Hard to Extreme |
Two rules worth carrying into any book you build. First, freeze the difficulty mix before you write the cover copy — “200 hard sudoku puzzles” is a contract with the reader. Second, keep the ratio consistent: a mixed Easy/Extreme book without a labelled split reads as broken, not varied.
From one page to a book you can publish
One puzzle page is not a book. KDP requires a minimum of 24 pages for a paperback, and a sudoku book that sells generally runs 80–120 pages with an answer key section, a title page, and consistent formatting throughout. Doing that a page at a time is not a workflow — it is a reason people abandon the project.
Book Studio is the paid product that does the rest: generate 50 or 100 unique puzzles in one run with duplicate checking across the whole set, lay them out on the trim size you have chosen, generate a matching answer key section, and export a KDP-validated interior PDF.
The free tool and the paid editor run the same generation and rendering code. What you are testing here is genuinely the thing.
For the rest of the production pipeline — difficulty bands, uniqueness at book scale, answer-key density, cover, price — see How to make a sudoku book for KDP.
Before you publish
Two free checks are worth running on any low-content book before it goes live:
- KDP Cover Calculator — computes the exact spine width and full cover dimensions for your page count and paper type.
- KDP Listing Checker — tests your title, subtitle and description against Amazon’s published metadata rules.
Frequently asked questions
Is this sudoku generator really free?
Yes, and it needs no account. Every visitor gets a set number of puzzles per day, shown as a counter next to the Generate button so you always know where you stand. The PDF you download has no watermark and no attribution line — it is yours to sell.
Can I use these puzzles in a book I sell on Amazon KDP?
Yes. The puzzles this tool generates are yours to publish and sell, including on Amazon KDP. There is no licence to attribute and no royalty. A single page is not a book, though: KDP requires a minimum of 24 pages for a paperback.
What size is the PDF, and is it KDP-ready?
Two pages — the puzzle and its answer key — at 6×9 inches, the most common puzzle-book trim. Numerals are laid out well above KDP's 7pt interior minimum and the pages carry proper margins. Two pages is a proof or a lead magnet, not a book. Assembling a full interior is what Puzzle Studio does.
Which board sizes can I make?
4×4 mini, 6×6, 9×9 classic, and 16×16 super. Classic 9×9 is the default because that is what sudoku-book buyers expect. Mini boards suit children's books and large-print titles; 16×16 is slower to generate because uniqueness has more work to do.
What do the difficulty levels actually change?
How many given numbers stay on the grid after the unique solution is filled. Very Easy leaves a lot of clues; Extreme removes as many as uniqueness still allows. The puzzle always has exactly one solution — a grid that admitted two answers is never shipped.
Does it generate an answer key?
Yes. Press Answer key above the preview and you get the same grid fully filled — and it rides along in both downloads, so the PDF is two pages and the ZIP holds two PNGs. It costs you nothing extra: the daily counter is per puzzle, not per render.
Can I make 50 different puzzles at once?
Not here — this tool is one page at a time by design. Bulk generation of large unique puzzle sets, with duplicate checking across the whole set, is the paid product. That is the honest line: this tool is genuinely useful on its own, and it is also a fair sample of what the full editor does.
Do you keep my puzzles?
No. Nothing about a generated puzzle is stored — no project, no database row, no file. The page is rendered and sent straight back to you. That is also why there is no shareable result link: there is nothing on our side to link to.
Why do I get a different grid each time I press Generate?
Fill and clue removal are randomised from a fresh seed, so pressing Generate again on the same settings gives you a different puzzle. That is deliberate — it is how you shop for a grid you like. Downloading the PDF re-renders the exact puzzle you are looking at, not a new one.
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