Logic puzzle

Sudoko

The classic 9×9 puzzle

Sudoko is a free online logic puzzle where you fill a classic 9×9 sudoku grid, placing the digits 1 to 9 once in every row, column and 3×3 region, with a new grid every day.

Duration: 5–12 min
Difficulty: Easy to hard
Skill: Logic
Price: Free

Play now — for free

How to play?

The sudoko you know, with a brand new grid every day. Nine rows, nine columns, nine 3×3 regions, and digits 1 to 9 to place without ever repeating one.

A 9×9 grid split into nine 3×3 regions.
Every digit from 1 to 9 appears exactly once per row.
Exactly once per column, and exactly once per region.
Pre-filled digits are locked: they are your footholds.

Why play?

The logic classic, with a fresh grid every day.
Puts focus and working memory to work.
Difficulty varies from day to day.

Tips

Scan a band of three regions for a single digit. If it already appears in two of them, only one row is left for it in the third, and often only one cell.
Start with the digits that appear most in the starting grid. Lock them with a long press: they are highlighted everywhere and the remaining cells stand out.
Look for pairs: if two cells in the same row only accept the same two digits, those digits are ruled out for every other cell in that row.
Drag across several empty cells to add a note to all of them at once. Each correct digit you place then clears that note from its row, column and region automatically.
A wrong digit still counts as a mistake after you undo it. When torn between two candidates, work elsewhere: the cell will often resolve itself.

Frequently asked questions

How do you play Sudoko?

Fill the 9×9 grid with the digits 1 to 9. Each digit must appear exactly once in every row, once in every column and once in every 3×3 region. Pre-filled digits are locked. You win when the grid is complete and correct.

Is Sudoko free to play?

Yes. Sudoko is free and runs in your browser, on desktop or mobile, with nothing to download. Today's grid can be played without an account. A free account unlocks the archive of past days, and SIWA+ (€18 a year) removes ads and adds advanced stats.

What is the difference between Sudoko and sudoku?

None in the rules: Sudoko is classic 9×9 sudoku. SIWA adds a daily grid shared by everyone, a score out of 1000 points with 1 to 3 stars, a daily leaderboard and streaks of consecutive days. For a shorter 6×6 version, try Sudolito.

Do Sudoko puzzles have a unique solution?

Yes. Every grid is generated by an algorithm and checked by a solver before it goes live, so it has exactly one solution. Difficulty depends on how many digits are given at the start, from about 36 on easy grids down to 22 on hard ones.

Is the daily sudoku harder on Sundays?

Yes. On Sundays the Sudoko grid is always rated hard. On other days the level varies between easy, medium and hard. The grid changes at midnight, your local time, and it is the same for every player, so you can compare your score on the daily leaderboard.