Sudoku Solver

Type or paste any 9 × 9 Sudoku and get the solution, plus a check that the puzzle has exactly one.

Type the clues into the grid, or paste a puzzle as 81 digits with 0 or a dot for empty squares. Arrow keys move between squares.

0 clues entered.

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About the sudoku solver

Stuck on a newspaper Sudoku, or want to check your answer? Enter the clues and the solver fills in the rest in a fraction of a second. It also tells you when a puzzle is broken: clues that clash, no possible solution, or more than one solution.

Would you rather solve it yourself? Every puzzle in our Sudoku game comes with hints that explain the next step, and the Sudoku techniques guide covers every technique you need.

How to use it

Click a square and type its digit. Arrow keys move around the grid; Backspace or 0 clears a square.
Or paste a whole puzzle: 81 digits in reading order, with 0 or a dot for each empty square.
Press Solve. Solved squares appear in blue next to your clues.
Change any clue to try again, or press Clear to start over.

Questions

How does the Sudoku solver work?

It searches every possibility systematically, always trying the square with the fewest options first, and stops once it knows whether there are zero, one or several solutions.

Why does it say my puzzle has more than one solution?

A proper Sudoku has exactly one solution. If clues are missing or mistyped, several grids can fit. A puzzle with fewer than 17 clues can never have just one.