Sudoku

How to play

Fill a nine-by-nine grid so each row, column and three-by-three box contains the digits 1 to 9 once. The starting clues are fixed, and each generated puzzle has one solution.

1. Choose a difficulty and start a new puzzle, or continue the board saved in this browser.
2. Select an empty cell and use the number pad or keyboard. Arrow keys move between cells.
3. Use Erase or Undo to revise an entry. Check and Hint are available when you need help.

Work from restrictions

Pick a row, column or box with several filled cells. List the missing digits mentally, then rule out any digit already present in the selected cell’s row, column or box. If only one candidate remains, you have a reason to enter it. After each placement, look again at the neighbouring units because one solved cell can force another.

A legal entry can still be wrong

A digit may avoid an immediate duplicate yet disagree with the final solution. Conflict highlighting helps catch repeated digits; Check provides a stronger check against the puzzle. A hint fills the selected editable cell, so select the place you want help with first. Try explaining the hint from the surrounding clues before continuing.

Your progress and privacy

No account is needed. Personal bests, preferences and saved progress stay in this browser where supported. They do not sync between devices. Keyboard and mouse test events are never saved. You can clear saved activity from the home page; the privacy notice explains consent and measurement.