Sudoku Solver
Stuck on a puzzle from a newspaper or an app? Type it in below. The solver can check it for mistakes, show you the next move with the reason, or fill in the whole answer.
0 of 81 filled
How to use it
- Enter the puzzle. Click a square and type the number, or paste all 81 numbers at once using 0 for empty squares.
- Check it. Press Check to look for repeated numbers, puzzles with no answer and puzzles with more than one.
- Take one step. Press Next step. The solver fills one square and explains why that number must go there.
- Or solve it all. Press Solve to fill every empty square at once.
On a keyboard, use the arrow keys to move and 1 to 9 to type. Backspace, Delete or 0 clears a square.
Next step, not just the answer
If you want to get better at Sudoku, the answer on its own does not help much. Next step finds one square you could have solved and tells you why. It looks for the two moves every solver uses most:
- A square with one option. Every other number is already in its row, column or box.
- A number with one home. In some row, column or box, a number fits in only one empty square.
When neither exists, the puzzle needs a harder technique, like a pair or an X-Wing. The solver says so and fills in one square to get you moving. Our strategy guide explains those techniques.
What the messages mean
| Numbers in red | The same number appears twice in a row, column or box. |
|---|---|
| No answer | The numbers can't all be right. Check each one against the original. |
| More than one answer | The puzzle is missing a clue, so it can be finished in different ways. |
| Exactly one answer | A proper Sudoku. Every puzzle on this site is like this. |
From the blog
Questions people ask
How do I use the Sudoku solver?
Click a square and type a number, or paste the whole puzzle as 81 characters with 0 or a full stop for empty squares. Then press Next step to see one move with the reason, or Solve to fill in the whole grid.
Can the solver tell me if a puzzle has a mistake?
Yes. Numbers that repeat in a row, column or box are shown in red. Check also tells you if the puzzle has no answer at all, which usually means a number was typed in the wrong place.
What does "more than one answer" mean?
A proper Sudoku has exactly one solution. If the solver finds two, the puzzle is missing a clue or one was copied wrong. Solve will still show one possible answer.
Is my puzzle sent anywhere?
No. The solver runs entirely in your browser. Nothing you type leaves your device.