How to use the Sudoku
- 1 Pick a difficulty and press “New game”. Easy puzzles start with 40 numbers, expert puzzles with about 24.
- 2 Select a cell and type a digit, or tap one of the number buttons. Use the arrow keys to move; Backspace clears a cell.
- 3 Switch on Notes (or press N) to pencil in candidates. Placing a digit removes it from the notes in its row, column and box.
- 4 Stuck? Hint fills the selected cell with the right digit. With “Show mistakes” on, wrong digits are marked in red.
- 5 Solve the grid to record your time. Copy the link to the puzzle to challenge a friend with the very same grid.
The rules of Sudoku
A Sudoku grid has 81 cells in 9 rows, 9 columns and nine 3×3 boxes. Some cells are given; you fill in the rest so that every row, every column and every box contains each digit from 1 to 9 exactly once. There is no arithmetic involved – the digits could just as well be letters or colours – only logic.
One solution, every time
Every puzzle here is generated on your device and checked to have exactly one solution, so you can always reason your way to the answer without guessing. That is the property that makes a Sudoku fair. Mathematicians have shown that a classic Sudoku needs at least 17 given numbers to have a unique solution; our expert puzzles give about 24, easy ones 40.
Difficulty levels
| Level | Given numbers | What it feels like |
|---|---|---|
| Easy | 40 | Many cells can be filled straight away |
| Medium | 33 | Needs scanning of rows, columns and boxes |
| Hard | 28 | Notes help: look for pairs and hidden singles |
| Expert | about 24 | Long chains of reasoning, few easy starts |
Tips for solving
- Scan for singles: look at one digit at a time and check where it can still go in each box.
- Use notes for cells with two or three candidates; when two cells in a unit share the same pair, those digits can go nowhere else in that unit.
- Work on the busiest areas first: rows, columns and boxes that are nearly full give the quickest wins.
Your progress stays with you
The game in progress and your statistics – games solved, streaks and best times per level – are kept in your browser, so you can close the page and continue later. Pin Sudoku to My tools to see your progress and streak on your start page.
Sources
Frequently asked questions
Is this Sudoku free?
Yes. You can play as many puzzles as you like, without an account and without ads.
Does every puzzle have one solution?
Yes. Each puzzle is checked when it is made: removing numbers stops as soon as a second solution would become possible.
Can I continue a game later?
Yes. Your game and statistics are kept in this browser, so the puzzle is still there when you come back.
How do I share a puzzle?
Use “Copy link to this puzzle”. The link contains the difficulty and a number that makes exactly the same grid for whoever opens it.
Do hints count?
A puzzle solved with hints counts as solved and keeps your streak going, but does not set a best time.
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