Sudoku Generator
Generate a sudoku with exactly one solution, at four difficulties, ready to print.
About the Sudoku Generator
Every puzzle is verified to have exactly one solution. Cells are removed from a complete grid one at a time, and any removal that would leave two possible answers is put back. That guarantee is the whole point: a sudoku with two solutions cannot be reasoned to an answer, only guessed at, and plenty of generators skip the check.
Difficulty here is set by how many clues remain — 45 for easy down to about 24 for expert. Clue count correlates with difficulty but does not determine it: a 30-clue puzzle needing only simple techniques is easier than a 35-clue one requiring an X-wing.
Each puzzle has a seed, so the same code always regenerates the same grid. That makes a puzzle shareable as five characters rather than as a wall of numbers.
How it works
Pick a difficulty and generate. Every puzzle has exactly one solution.
Play it here, or print it — the print layout drops everything but the grid.
Each puzzle has a seed, so the same code always gives the same puzzle.
Frequently asked questions
- Does every sudoku have only one solution?
- A properly constructed one does, and every puzzle here is verified. Cells are removed only if the grid still has a unique answer — a sudoku with two solutions cannot be solved by logic, only guessed.
- What is the minimum number of clues in a sudoku?
- Seventeen, proven by exhaustive computer search in 2012. No 16-clue puzzle can have a unique solution. The expert setting here stops well above that, around 24.
- How is sudoku difficulty determined?
- Partly by clue count and partly by which solving techniques are needed. Fewer clues generally means harder, but a 30-clue puzzle needing only scanning is easier than a 35-clue one requiring advanced patterns.
- Can I get the same puzzle again?
- Yes — each puzzle has a seed, and entering it regenerates the identical grid. That makes a puzzle shareable as a short code rather than a picture.
- Can I print the puzzle?
- Yes. The print layout drops the interface and leaves the grid, so it prints as a clean puzzle sheet.
Privacy
Everything happens locally. Your files are read by your own browser, processed on your device, and never uploaded — closing the tab is all it takes to erase them.
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