Sudoku
Place the digits 1 to 9 so that no row, column or box repeats a number. Every grid is created by our own generator and checked to have one single solution.
How to play Sudoku
- Fill the 9×9 grid so that every row, every column and every bold-outlined 3×3 box contains each digit from 1 to 9 exactly once.
- Some digits are given at the start and cannot be changed. Every puzzle has exactly one solution, and you never need to guess.
- Tap a square, then tap a number (or type it). Tap the same number again, or use Erase, to clear it.
- Switch on Notes to pencil in small candidate digits. Placing a digit removes it from the notes in the same row, column and box automatically.
Controls
- Arrow keys: move 1–9: enter a digit Shift + 1–9: toggle a note
- N: notes mode Backspace / 0: erase Z or Ctrl+Z: undo H: hint
Tips
- Start with the digit that already appears most often and look for the boxes still missing it.
- When a box, row or column has only one empty square left, the missing digit is forced.
- Pencil in candidates once the easy placements dry up — patterns such as pairs become much easier to spot.
- Tap a placed digit to highlight every copy of it on the board.
FAQ
How do you play Sudoku?
Fill every empty square with a digit from 1 to 9 so that each row, each column and each bold 3×3 box contains every digit exactly once. Start where a row, column or box is nearly full, and use notes to track the digits a square could still hold.
How are the difficulty levels decided?
We grade every puzzle by the hardest solving technique it needs. Easy needs only singles, Medium adds pairs and locked candidates, Hard adds triples, X-wings and XY-wings, and Expert needs something tougher still.
What does the Mistakes button do?
With mistakes shown, any digit that does not match the solution turns red. Hide them if you prefer to find your own errors.
Is my puzzle saved?
Yes. Your grid, notes and timer are saved in this browser for each level, so you can close the page and pick up where you left off.