Free Printable Hard Sudoku
Four hard grids at 27 clues. Expect to keep candidate lists in the margins — these do not fall to scanning.
Free and unlimited, no account. Every grid is generated fresh in your browser and has exactly one solution.
How the difficulty is set
Difficulty here is the number of given clues: about 41 on easy, 33 on medium and 27 on hard — approximate because clues are only removed while the grid keeps a single solution, so a generator sometimes stops a cell or two short. Every grid is generated with a full valid solution first and clues removed afterwards, so each one has exactly one answer — there is never a puzzle that needs guessing, and the answer key is the original solution rather than something re-derived.
Printing these
Print puts the grids on the sheet and hides the controls. The PNG is rendered at twice screen size so the rules between boxes stay sharp. For the answer key, switch answers on before downloading — it saves under its own filename so the two never get mixed up.
Turning these into a book
These puzzles are yours to use, including in a book you sell. Assembling one is the part this page does not do — a paperback needs a hundred grids at a fixed trim with paired solution pages and a gutter that grows with page count. KDP Creator builds that, and the royalty calculator prices it first.
