Sudoku solver
Type in the given digits, then press Solve for the answer or Next step for one explained move at a time. Everything runs in your browser.
Enter a puzzle to begin.
How to use the solver
- Enter the puzzle. Type the given digits into the grid, or paste an 81-character string with 0 or . for blanks.
- Check it. Press Check to confirm the puzzle has exactly one solution.
- Solve or step through. Press Solve for the full answer, or Next step to reveal one logical move at a time with an explanation.
What the messages mean
| Unique solution | A proper Sudoku. Solve it by hand, step through it, or reveal the answer. |
|---|---|
| More than one solution | The puzzle is missing a given. Real Sudokus have exactly one answer. |
| No solution | A digit is in the wrong place or repeated in a row, column or box. |
Rather solve one yourself? Play a fresh Sudoku or today's daily puzzle, and read our solving techniques.
Frequently asked questions
How does the Sudoku solver work?
Enter the starting digits and press Solve. The solver searches every possibility with constraint checking, so it finds the answer to any valid 9×9 Sudoku in a fraction of a second, entirely in your browser.
Can the solver explain the next step instead of the whole answer?
Yes. Press Next step: the solver finds the next naked or hidden single, explains why that digit must go there, and fills just that one cell.
How do I know if a Sudoku has a unique solution?
Press Check. The solver counts solutions and tells you whether the puzzle has exactly one, several (the puzzle is broken), or none (there's a mistake in the givens).
Can I paste a puzzle?
Yes. Paste 81 characters into the text box, row by row, using 0 or . for empty cells, then press Load.