- Difficulty
- Expert
- Time
- 00:00
- Checks
- 0
Select a square and place a number.
expert Sudoku
Follow the proof through deeper patterns.
Expert Sudoku uses the same three rules as every standard grid: each row, column, and 3 × 3 box must contain 1 through 9 exactly once. The difference is the length and depth of the logical path, not a change in the rules.
The puzzle shown here is designed for about 20 minutes. Its verified solution takes 66 supported steps and uses Hidden Single, Locked Candidates, Naked Pair, and Naked Single. It has exactly one solution, so no branch or random guess is required.
Expert grids reward accurate candidates, locked candidates, and reserved pairs. Treat advanced techniques as eliminations that simplify the grid, not shortcuts to a guess.
Use Notes to keep candidates visible, Check when you want to audit the current grid, and Hint for the next logical idea rather than a filled answer. Progress is stored on this device, so a longer solve can be paused and resumed without an account.
Common questions
What makes this Sudoku expert?
The rating reflects the verified solving path: 66 steps using Hidden Single, Locked Candidates, Naked Pair, and Naked Single. Difficulty is based on deductions, not on guesswork or simply counting the givens.
How should I approach an expert Sudoku?
Expert grids reward accurate candidates, locked candidates, and reserved pairs. Treat advanced techniques as eliminations that simplify the grid, not shortcuts to a guess.
What should I do when I get stuck?
Verify every candidate in the affected regions, compare repeated pairs, and ask for an explanatory hint only after simpler deductions have been exhausted.
Can I pause and continue later?
Yes. Your entries, notes, elapsed time, and completion state are saved locally in this browser and restored when you return.