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Sudoku generator

Printable sudoku from tiny 4×4 grids for five-year-olds to hard 9×9s. Each puzzle is checked to have exactly one solution.

Grid
Difficulty
Puzzles per page

Each puzzle: 0 clues, digits 1–9.

Sudoku

9×9 · easy

Fill every row, column and bold box with the digits 1–9, each exactly once.

Generating…

Solutions

How the sudoku generator works

Making a sudoku is easy; making one that is fair is the hard part. A fair puzzle has a single answer you can reach by reasoning. The generator fills a complete valid grid at random, then removes digits one at a time, and after each removal a solver checks the grid still has exactly one solution. Step through it yourself:

See how a sudoku with one solution is made

1234341221434321

Start with a complete, valid grid: every row, column and 2×2 box holds 1–4 once.

Clues left: 16 · step 0 of 16

Which size should I print?

GridDigitsBoxesTypical age
4×41–42×25–7
6×61–62×37–10
9×9 easy1–93×39+ and beginners
9×9 hard1–93×3Regular solvers

A first strategy to teach

Pick one digit, say 1, and scan every box for it. If a box is missing a 1 and the 1s in neighbouring rows and columns rule out all but one empty cell, write it in. Repeating this “cross-hatching” for each digit solves most easy puzzles on its own.

Questions people ask

Does every sudoku have exactly one solution?

Yes. After each digit is removed, a solver counts the ways to finish the grid. If there is more than one, the digit goes back. So every printed puzzle can be solved by logic alone, without guessing.

What is a good sudoku for kids?

Start with 4×4 (digits 1–4, 2×2 boxes), which most children aged 5–7 can solve after one example. Move to 6×6 around age 7–9, then easy 9×9.

How are the difficulty levels different?

Difficulty is set by how many clues remain. An easy 9×9 keeps about 40 clues, medium about 32 and hard about 26. Fewer clues usually means longer chains of reasoning.

Can I print several sudoku puzzles on one page?

Yes. Choose 1, 2, 4 or 6 puzzles per page. Each is different, and the answer page prints the solutions in the same order.

What are the rules of sudoku?

Fill the grid so every row, every column and every box contains each digit exactly once: 1–9 on a 9×9, 1–6 on a 6×6, 1–4 on a 4×4.

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