Sudoku Solver
Enter or scan any 9×9 sudoku. Get the answer instantly, or step through it one logical move at a time.
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How to use the sudoku solver
- Enter the givens. Tap a cell and a number, or type with the keyboard (arrows move, space skips a cell). Or press Scan a photo and pick a straight-on picture or screenshot of the puzzle. An AI vision model reads the digits, and you can check and fix them before solving.
- Choose how much help you want. Solve this cell reveals just the selected square. Next step places one number and explains the logic behind it. Solve it fills the whole grid.
- Read the verdict. The solver checks for clashing givens, grids with no solution and grids with more than one solution, and tells you how far plain singles get before harder techniques are needed.
How the solver works
It works in two stages. First it solves the way a person would: it keeps placing naked singles (a cell with only one possible number) and hidden singles (a number with only one possible cell in a row, column or box), and explains each move. When neither move applies, it finishes with a depth-first search that always tries the cell with the fewest candidates first. That search also counts solutions, so it can warn you when a puzzle is broken. Everything runs in your browser. Only the optional photo scan sends anything to our server.
To learn the techniques behind the steps, read how to play sudoku. To play rather than solve, try today’s daily sudoku or print today’s three puzzles.
Questions players ask
Can a sudoku solver solve any puzzle?
Any valid 9×9 sudoku, yes. Search always finishes, and it finds every solution if there is more than one. If the grid has no solution, a given was most likely copied wrong, and the solver tells you so.
How many numbers do I need to enter?
All the givens from your puzzle. A sudoku needs at least 17 givens to have a single solution, a minimum proved by McGuire, Tugemann and Civario in 2012.
Can I solve a sudoku from a photo?
Yes. Press "Scan a photo of a puzzle" and choose an image. A vision model reads the grid through our server; always check the digits it fills in before solving, since smudges and handwriting can be misread.
Is using a sudoku solver cheating?
Only if you want it to be. Use Next step or Solve this cell to get unstuck without spoiling the whole puzzle, and read why each move works.
Why does it say “more than one solution”?
A proper sudoku has exactly one answer. If you get this message, a given is probably missing or wrong, or the puzzle came from a source that doesn’t check its grids.