Sudoku
The classic 9×9 logic puzzle — every puzzle has exactly one solution
⌨️ Type digits to fill · Backspace to clear · Arrow keys to move
Sudoku Rules
Sudoku is a world-famous number logic puzzle. Fill the 9×9 grid with digits 1–9 so that every row, every column and every 3×3 box contains each digit exactly once. The pre-filled digits are your clues — use pure logic to work out every empty cell. All puzzles on this site are generated on the fly and guaranteed to have exactly one solution.
Tips for Beginners
- Elimination: a digit already present in a row, column or box cannot be repeated inside that unit.
- Last remaining number: if a cell's row, column and box already contain 8 different digits, the cell must hold the missing one.
- Start with the fullest units: rows, columns or boxes with the most clues are usually the easiest to crack.
- Use Check: stuck? Hit the Check button to quickly spot any mistakes in red.
FAQ
What are the rules of Sudoku?
Fill the 9×9 grid with digits 1–9 so that every row, every column and every 3×3 box contains each digit exactly once. Deduce all empty cells from the given clues.
Does every puzzle have a unique solution?
Yes. All puzzles are generated on the fly and verified to have exactly one valid solution.
What is the difference between the three difficulties?
Harder levels start with fewer clues: Easy has about 43 givens, Medium about 35, and Hard about 29.
Is Sudoku good for your brain?
Sudoku trains logical reasoning, concentration and working memory — a popular mental workout for all ages.