Puzzle generator
Printable Sudoku
Generate fresh sudoku puzzles at five difficulty levels and print them at any size. Every grid is verified to have exactly one solution, and every set comes with a matching answer key. Nothing to install, nothing to sign up for.
Four steps
How to print sudoku puzzles
- 1
Pick a difficulty
Choose Easy, Medium, Hard, Expert or Evil — the harder the level, the fewer starting clues.
- 2
Set how many
Choose the number of puzzles and how many to fit on each page: one, two or four.
- 3
Add the key
Leave the answer key switched on to append solution pages after the puzzles.
- 4
Print or download
Send it straight to your printer, or download PDF and print at 100% scale.
A sudoku generator, not a pile of static PDFs
Most free sudoku sites host a fixed library: a few hundred pre-made puzzles that everyone downloads and that your students will find online in thirty seconds. This tool builds a brand-new grid every time you press shuffle, so the puzzle in your hand has never existed before and cannot be searched for.
The generator works in two stages. First it fills a blank 9×9 grid with a complete, valid solution using randomised backtracking. Then it removes clues one at a time, re-solving after every removal to confirm the puzzle still has exactly one answer. When it can no longer remove a number without creating ambiguity, or it has hit the clue target for your chosen difficulty, it stops.
Choosing the right difficulty
| Level | Clues | Typical time | Best for |
|---|---|---|---|
| Easy | ~40 | 5–10 min | Beginners, younger solvers, warm-ups |
| Medium | ~32 | 10–20 min | Daily-newspaper standard |
| Hard | ~27 | 20–35 min | Regular solvers |
| Expert | ~24 | 35–60 min | Advanced techniques required |
| Evil | ~22 | 60 min+ | Serious solvers only |
A 9×9 sudoku needs at least 17 clues to be uniquely solvable — that is a proven mathematical minimum — so anything below the low twenties is genuinely punishing.
How to solve sudoku, briefly
Fill the grid so every row, every column and every 3×3 box contains the digits 1 to 9 exactly once. Three techniques will carry you through most puzzles:
- Scanning — pick a digit and check each box: if only one cell in that box can legally hold it, write it in.
- Naked singles — if a cell has only one candidate left after eliminating everything in its row, column and box, that is the answer.
- Pencil marks — write small candidate digits in the corners of each cell. Pairs and triples that repeat within a unit let you eliminate those candidates elsewhere. Print at one puzzle per page if you rely on this.
Printing tips for classrooms and clubs
Four puzzles per page is the sweet spot for a class set — it keeps the paper count down while leaving grids big enough for a pencil. Print the puzzle pages only, keep the answer pages for yourself, and note the seed if you might need to reprint a lost sheet.
For a puzzle booklet, generate twelve puzzles at two per page, print double-sided and fold. If you would rather work on screen, download the SVG and annotate it in any vector editor.
Related printables
If you are assembling an activity pack, the maze generator and word search maker both produce solution pages too, and the coloring page generator gives younger children something to do at the same table. For number practice rather than logic, try the math worksheet generator.
Answers