Sudoku Generator

How the Sudoku Generator Works

Every puzzle you generate here is built from scratch in two steps. First, a randomised backtracking algorithm fills a complete, valid 9×9 grid — all 81 cells, with every row, column, and 3×3 box containing the digits 1 through 9 exactly once. Second, the generator removes digits one cell at a time. After each removal it runs a solution-counting check on the remaining grid: if more than one solution would exist, the digit is put back and a different cell is tried.

The result is a puzzle with exactly one solution, every time. You will never hit a position where guessing is required because the puzzle is ambiguous. Difficulty is controlled by how many given digits remain: easy puzzles keep around 38 clues, while extreme puzzles are pared down to 17 — the proven mathematical minimum for a uniquely solvable Sudoku.

Because puzzles are generated randomly on each request, no two clicks of the Generate button produce the same set. Generate as many as you like — it's free and unlimited.

Generator vs. Printable vs. Solver

This page is for creating new puzzles on demand — pick a difficulty, generate, and either solve right here on screen or print the batch. If your goal is preparing paper worksheets with per-level guidance — for a classroom, a flight, or a puzzle club — head to our printable Sudoku puzzles hub, which is built around print layouts of up to 9 puzzles per sheet at every difficulty.

Going the other direction — you already have a puzzle and want the answer? The Sudoku solver takes any grid you enter and computes the solution instantly. And if you just need empty grids to copy a puzzle onto, grab a blank Sudoku grid.

Frequently Asked Questions