It has the fewest clues of the four levels: 24 givens, against 28 for Hard, 33 for Medium and 40 for Easy. Fewer givens usually means more candidates to track and a longer solve. The level is a clue count, not a rating of the solving techniques a grid needs, so we do not call any grid the hardest Sudoku ever.

Can a puzzle with 24 clues still have one solution?

Yes. Each clue is removed only after a solver confirms the grid still has exactly one solution, and a check that runs past its step limit keeps the clue. The same solution drives the completion check, hints and the printed answer key.

Is this the same as evil or extreme Sudoku?

Those are level names on other Sudoku sites, each graded their own way. Expert here is defined only by its clue count, the lowest this page offers, and is the one to pick for a very hard puzzle.

Can I print very hard Sudoku puzzles?

Yes. Print puzzle prints only the starting digits in a large black and white grid, and Print answers prints the full solution on its own sheet. Press New puzzle first for a different Expert grid.

Very Hard Sudoku: Expert Level

This page opens on the Expert level, the sparsest Sudoku the generator makes: each 9×9 grid starts with 24 givens, and now and then 25, or very rarely 26, when six tries find no sparser grid with one solution. That leaves 55 to 57 empty squares, and every puzzle still has exactly one solution, proved by a solver before each clue was taken away. Expect to keep pencil marks for most of the grid. Notes, Undo and a running timer are there; Hint fills a square but marks the session assisted, so an unassisted solve stays an honest one. Print puzzle and Print answers put the grid and its answer key on paper.

SUDOKU · EXPERT · 24 CLUES

Fill every row, column and box

0:00

Difficulty

Choose a square, then press a number.

Keyboard: focus the board, use arrows to choose a square, then press 1–9. Notes are pencil marks kept in this browser. Every generated puzzle has exactly one solution; the level sets the clue count (Easy 40, Medium 33, Hard 28, Expert 24, now and then 25 or, rarely, 26). Print puzzle prints the starting grid without your entries; Print answers prints the solution.

Common questions

How hard is Expert?: It has the fewest clues of the four levels: 24 givens, against 28 for Hard, 33 for Medium and 40 for Easy. Fewer givens usually means more candidates to track and a longer solve. The level is a clue count, not a rating of the solving techniques a grid needs, so we do not call any grid the hardest Sudoku ever.
Can a puzzle with 24 clues still have one solution?: Yes. Each clue is removed only after a solver confirms the grid still has exactly one solution, and a check that runs past its step limit keeps the clue. The same solution drives the completion check, hints and the printed answer key.
Is this the same as evil or extreme Sudoku?: Those are level names on other Sudoku sites, each graded their own way. Expert here is defined only by its clue count, the lowest this page offers, and is the one to pick for a very hard puzzle.
Can I print very hard Sudoku puzzles?: Yes. Print puzzle prints only the starting digits in a large black and white grid, and Print answers prints the full solution on its own sheet. Press New puzzle first for a different Expert grid.

Every generated puzzle has exactly one solution, checked by a solver before each clue is removed, and every given agrees with that solution. Conflicts are checked by row, column and 3×3 box; the level sets the clue count, which is not a measured human solving time.