Hard Sudoku to print (free PDF)
Download free hard Sudoku puzzles to print in PDF, ready for A4 or US Letter. A serious workout for experienced solvers.
Sudoku book (PDF)
Download the free hard sudoku book in PDF: 20, 60 or 120 puzzles, with the solutions in a separate PDF. Ready to print on A4 or US Letter.
Sample puzzles
Why this level?
A hard Sudoku starts from about 26–28 clues, so scanning alone rarely cracks it. You'll rely on candidate notes and techniques like naked or hidden pairs to make progress.
How to print
Click "Download book", open the PDF and choose A4 or US Letter. Six puzzles per page; check yourself with the separate solutions PDF.
Solving tips
Fill in candidates fully, then hunt for pairs and triples that eliminate other candidates in the same row, column or box.