20–24 clues · typical solve 40 minutes to over an hour
Printable expert sudoku puzzles: the hardest free PDF grids
About a quarter of the grid filled in, and one solution to reach.
Set an expert run
difficulty is already set to expert; adjust the rest
1–60 · the solver checks each puzzle for a single solution before adding it
This sample switches to your own puzzles when the run finishes.
What a expert sudoku asks of you
Expert puzzles carry 20 to 24 clues, close to the floor for a sudoku with one answer. The proven minimum is 17, and puzzles with 17 clues are rare enough that enthusiasts catalogue them one by one. At 20 to 24 the generator can produce sparse, sound grids on demand. Expect the first ten minutes to give you nothing beyond a fully pencilled board.
From there you work with chains and eliminations: X-wings, unique rectangles and forcing chains, the techniques you reach for once nothing simpler is left. Many solvers spread an expert grid over several sittings. The grid tests whether you can keep a board consistent, in your head and on paper, for an hour, and speed has little to do with it.
Two warnings. Print one per page, because you will need the space for candidate marks, and a cramped grid invites a misread digit. And print the answer key. On a grid this sparse, one wrong entry early on can survive forty moves before a contradiction shows up, and checking the finished grid saves you an evening of doubt.
Printable expert sudoku: questions
How many clues does an expert sudoku have?
Between 20 and 24. An easy puzzle starts with 38 to 45, so an expert grid asks you to work out nearly three quarters of the board from a quarter of it.
What is the minimum number of clues a sudoku can have?
Seventeen. Researchers proved in 2012 that no valid sudoku with a unique solution has sixteen or fewer clues. Our expert range sits above that floor because puzzles with 17 clues are rare, and a generator cannot produce them reliably on demand.
Are expert puzzles still solvable without guessing?
Yes. The solver confirms each puzzle has one solution, and you can reach a unique solution by logic. It may take advanced techniques and patience, but a deduction exists at every stage.
Why do expert puzzles take longer to generate?
The generator tests each clue removal. To get down to 22 clues it tries removing far more cells than it keeps empty, running the solver each time to check the puzzle still has one answer. An expert batch does more work per puzzle than an easy one.
Try another level
Expert is the hardest level the generator makes. If these take longer than you would like, drop back a level: the logic stays the same, with more of the grid already filled in.
- Easy printable sudoku38–45 cluesPlenty of clues, and a solving path you can find by scanning alone.typical solve: 5–10 minutes
- Medium printable sudoku30–37 cluesThe everyday sudoku, at the level a newspaper prints midweek.typical solve: 10–20 minutes
- Hard printable sudoku25–29 cluesSparse grids that open up once you reason about where each digit cannot go.typical solve: 20–40 minutes
Or head back to the free printable sudoku generator for a mixed run, or take a set of printable sudoku with answers.