Unique-solution Sudoku maker
Generate a printable Sudoku with a separate solution. Removing a cell is allowed only while exactly one solution remains.
Your inputs
Start with the example values, then replace them with your own. For tables, keep the vertical bar separators and use a dot for decimals.
This activity is for entertainment and organizing informal games. Random assignments and entered skill scores do not measure personal worth or guarantee fairness.
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Result and workspace
Use the start button to open your result or activity.
How it works
Shuffle a valid completed 9×9 grid using row, column and digit permutations. Attempt to remove the requested number of cells; a backtracking counter stops at two solutions. The actual removed count can be lower. Empty-cell count is not a calibrated difficulty rating.
Worked example
These sample results use the original example inputs in the form. They do not change when you edit your inputs; your own result appears in the workspace.
- Empty cells: 40
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|
| · | 8 | · | · | 1 | 9 | 7 | 3 | · |
| 9 | · | 1 | 3 | 7 | 6 | 5 | · | 2 |
| · | · | · | 8 | · | · | · | · | 9 |
| 5 | 2 | · | · | 3 | · | · | 6 | 7 |
Read the result carefully
Results depend on the values and assumptions shown above. Change one input at a time to see its effect. A blank or unavailable result means the data does not support a calculation; it is not zero.