Classic Sudoku: play free online
Classic 9 × 9 sudoku online, free: every grid has a single solution, from easy grids solved with simple deductions to expert ones that take more.
Play Classic SudokuFree, zero ads, no sign-up, on mobile and desktop.
How to play
Fill the grid so that every row, every column and every 3 × 3 box contains each digit from 1 to 9 exactly once.
Tips to get better
- Look for “hidden singles” first: in a box, row or column, a digit that has only one possible cell left.
- Note candidates in tricky cells: a cell with a single candidate left fills itself.
- Naked pairs: two cells in a row that accept only the same two digits reserve them; remove those digits from the rest of the row.
- Box-line reduction: if in a box a digit can only go on one row, it is excluded from that row in the other boxes.
- Work digit by digit (all the 1s, then all the 2s…): often faster than cell by cell.
What this game trains
- Logical reasoning: deduce the solution from the rules, without guessing.
- Attention and focus: quickly pick out the right item among distractors.
Levels
Easy · Hard · Expert · Hardcore — each level has its own leaderboard.
Challenge your friends
At the end of a game, send your score as a link: your friend plays exactly the same game and you compare your times. There is also a daily challenge and tournaments.