Sudoku
Classic number puzzle, 4 levels
Keyboard: arrows move, 1–9 fill, Backspace erases, N toggles notes, Z undoes. Best times:
About the Sudoku
Endless Sudoku puzzles generated in your browser, each with exactly one solution. Choose Easy, Medium, Hard or Expert, then fill the grid so every row, column and 3×3 box contains the numbers 1 to 9. Pencil in candidates with Notes, undo any move, ask for a hint when you're stuck and turn mistake highlighting on or off. The board highlights the row, column, box and matching numbers for the cell you're on, and the number pad shows how many of each digit are left. Your game is saved automatically, so you can close the tab and finish later, and your best time for each level is kept.
- Pick a difficulty.
- Select a cell and tap a number (or type 1–9). Turn on Notes to pencil in candidates.
- Fill every row, column and box with 1–9 to win. Use Hint or Undo if you get stuck.
Solving techniques, from easy to expert
Start with singles: a cell where only one number fits, or a number that can only go in one cell of a row, column or box. On harder puzzles, pencil in candidates with Notes and look for pairs: if two cells in a box can only be 4 or 7, no other cell in that box can be 4 or 7. Expert puzzles also need pointing pairs, X-wings and similar patterns, but every puzzle here can be solved by logic alone, without guessing.
Using notes well
Turn on Notes and fill in every candidate for a box or row before you commit to numbers. When you place a correct number, it is cleared from the notes in its row, column and box automatically, so new singles appear as you go.
Frequently asked
How do you play Sudoku?
Fill the 9×9 grid so that every row, every column and every 3×3 box contains each number from 1 to 9 exactly once. Some numbers are given at the start, and there is only one correct solution.
What is the best Sudoku strategy for beginners?
Scan each box for numbers that can only go in one place, then look for cells with a single possible number. Use Notes to pencil in candidates on harder puzzles and remove them as you fill cells.
How are the difficulty levels different?
Harder puzzles start with fewer numbers (40 on Easy down to about 23 on Expert) and need more advanced logic to solve without guessing.
Does every puzzle have a unique solution?
Yes. Each puzzle is checked by a solver while it is created, so there is always exactly one solution.
Is Sudoku free to play?
Yes. It's free with no download, no sign-up and no in-app purchases. It works on phones, tablets and computers.
Is my best score saved?
Where the game has a high score, it is saved in your browser on this device.
Can I turn off mistake highlighting?
Yes. Untick Highlight mistakes for a classic challenge where wrong numbers aren't marked; numbers that clash with the same number in a row, column or box are still outlined.
Will I lose my game if I close the page?
No. Your puzzle, notes and time are saved in your browser and the game resumes where you left off.
Is what I type sent to a server?
No. The tool runs entirely in your browser and there's no server behind it, so what you type never leaves your device and nothing is stored. You can check: it keeps working if you go offline after the page has loaded.
More from the Games drawer
Other tools kept in this drawer, plus a few favourites from the bench.