About Printable Sudoku
A puzzle generator built the way a small print shop would do it: set the run, pull a proof, print it.
What the site does
This site makes printable sudoku PDFs to order. You choose how many puzzles, how hard, how many to a page and what size paper, and it builds the puzzles and the document while you wait. We built it because most free printable sudoku on the web comes as a fixed PDF of forty puzzles in one layout, and that is rarely the sheet you want.
How the generator makes puzzles
The generator starts each puzzle from a complete, valid 9×9 grid produced by randomised backtracking. It then removes clues one at a time in random order. After each removal a solver counts the solutions of what is left, stopping as soon as it finds a second one. If it finds two, the generator puts the clue back, so it keeps only removals that leave a unique solution.
The solver tracks candidates as bitmasks and tries the most constrained cell first, which makes it fast enough to run after each removal. This check costs the most time during generation, and plenty of free generators skip it. We run it because a grid with two answers forces you to guess at some point.
Clue count sets the difficulty: easy 38–45, medium 30–37, hard 25–29 and expert 20–24. The PDF prints each puzzle’s count under its grid, so you can check the label against a number.
Everything runs in your browser
No server takes part in making your puzzles. The generator, the solver that checks them and the code that lays out the PDF all run as JavaScript on your own machine, with generation on a background thread so the page stays responsive during a large batch. Your run never leaves your machine, which is why the download is instant and why we store nothing you generate. The privacy page covers the details.
Cost
Nothing. You need no account and give no email address, and the site has no trial, watermark or paid tier. Print the puzzles for your class, your family or your newsletter. A computer generates the grids, and we claim no ownership of what you produce.
What we plan to add
Next on the list are more grid sizes, large-print layouts and puzzle variants. If something about the sheets got in your way after a few runs, we want to hear about it. We settled the current layout by printing many pages and adjusting, and we will keep working that way.