Free Sudoku Maker

Generate a fresh printable sudoku in one click. Pick a difficulty, print it, and use the answer key to check. Free, no sign-up.

How to solve sudoku without guessing

Every puzzle here has exactly one solution reachable by logic, so if you are stuck, there is a move available. Three techniques cover most puzzles.

Scanning. Pick a number, say 7. Look at each band of three boxes and find where 7 already appears. Those rows and columns are blocked. Frequently only one cell in a box remains, and the 7 goes there. Work through 1 to 9 this way and easy puzzles largely fill themselves.

Single candidates. For a stubborn cell, list which numbers are still possible given its row, column, and box. If only one survives, it is forced. This is slower than scanning and it breaks open medium puzzles.

Pairs. If two cells in the same row, column, or box both have exactly the same two candidates, those two numbers belong to those two cells in some order. They are eliminated from every other cell in that group. Spotting pairs is usually what cracks a hard puzzle.

What the difficulty settings change

Difficulty here is the number of starting clues. Easy leaves 38 numbers filled, medium 32, hard 26. Fewer clues means fewer places to begin scanning and more reliance on candidate elimination. The generator removes numbers one at a time and re-checks uniqueness after each removal, so a hard puzzle is hard but never ambiguous. A puzzle that requires trial and error is a broken puzzle, and that check is what prevents it.

Below about 24 clues, puzzles become unreliable to generate quickly, which is why hard stops at 26. The mathematical minimum for a unique sudoku is 17 clues, and puzzles at that level take specialized search to construct.

Printing tips

Print one puzzle per page for comfortable pencil work. Use the answer key toggle before printing if you want the solution on the same sheet, or print twice with it hidden and shown to keep the key separate, which is what teachers usually want. Grid lines are drawn as vectors so they stay sharp, and the print view drops navigation and ads automatically.

For classroom sets, generate and print each puzzle separately rather than photocopying one sheet. Every generation produces a different puzzle, which stops students comparing answers across desks.

About the free sudoku maker

Fill the grid so every row, column, and 3x3 box has the numbers 1 through 9. Each puzzle has one solution. Easy puzzles give more starting numbers, hard puzzles give fewer. It runs fully in your browser.