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Printable sudoku
Make a set of up to twelve printable sudoku puzzles with answer keys, at four difficulty levels and one, two or four to a page. Each grid is generated on your device when you ask for it, with no puzzle bank behind it, and checked for exactly one solution before it prints. There is no watermark and no account, and nothing is uploaded.
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How this generator works
Each sudoku is built in two stages, and the first involves no searching. A complete, valid solution grid comes from one known-good pattern, changed only in ways that cannot break it: relabelling the nine digits, shuffling the three rows inside each band, shuffling the bands themselves, doing the same to columns and stacks, and sometimes transposing the whole grid. Every one of those moves keeps the row, column and box rules intact, so the finished grid is correct by construction. There are enough distinct combinations that two visitors pressing "New puzzles" are very unlikely to get the same grid.
The second stage removes clues, and it is where each puzzle is checked for a single solution. Cells are cleared two at a time in 180-degree rotational pairs, which gives a printed sudoku its familiar symmetry. After every removal a backtracking solver counts how many ways the grid can now be completed, stopping as soon as it finds a second. A removal is kept only if exactly one solution remains; otherwise both cells are filled in again. Clearing continues until the grid reaches the target clue count for the chosen difficulty or no symmetric pair can come out without allowing a second solution. Each puzzle is labelled with its number, its difficulty and its real clue count, so you can see which happened, and the Details panel below the sheet shows the range of clue counts across the set. Twelve expert puzzles take a moment to generate, because every grid gets this check after every removal and the clue-removal pass runs up to twelve times to get as close to the target as it can. Print at 100% or "Actual size"; "Fit to page" rescales the grid.
Difficulty here is set by clue count alone: a 27-clue grid that falls to plain scanning is easier than a 30-clue grid that needs an X-wing. Keeping the clues symmetric is a choice about looks, and it costs clues. The proven minimum for a sudoku with any pattern of clues is 17 givens, but the grids that reach it are asymmetric, and insisting on rotational symmetry throws away most of that search space, so the symmetric grids here bottom out in the low twenties and expert targets 24. Some grids finish below that target and some stop a clue or two above it, so trust the count printed above each puzzle more than the difficulty name.