How to Play Sudoku
- Pick a difficulty: Easy, Medium or Hard. The fewer numbers you start with, the harder the puzzle.
- Fill the 9×9 grid so that every row, every column and every 3×3 box contains the numbers 1 to 9 with no repeats.
- Tap a cell, then a number. Repeated numbers are marked in red, and cells in the same row, column and box are highlighted.
- Use Notes to jot down candidates, Undo if you make a mistake and Hint if you get stuck. You win when the grid is complete and correct.
Sudoku Rules and Solving Tips
A good Sudoku has exactly one solution and can be solved by logic, without guessing. Every puzzle on this page is generated on your device and checked to make sure it has only one possible solution.
Start with the numbers that appear most often on the board and look for the row, column or box that is missing just one. Then use Notes to write down the candidates for each cell: if a number fits in only one cell of a box, it goes there. If two cells in the same row have exactly the same two candidates, those two numbers cannot go in any other cell of that row.
Everything runs in your browser and nothing is sent to any server. Your game in progress and your best times are saved on your device, so you can close the page and pick up later.
Good to Know
- Your best time only counts if you solve the puzzle without using hints.
- The game and records are saved only in this browser: if you clear the site data, they are lost.
- The timer stops when you switch tabs or minimize the browser.
Frequently Asked Questions
Do all puzzles have a unique solution?
Yes. Each puzzle is generated on your device and checked to have only one solution, so it can always be solved by logic.
How do you play Sudoku?
Fill the 9×9 grid so that every row, every column and every 3×3 box contains the numbers 1 to 9 without repeating. Start with the squares where only one number fits.
What is the difference between the levels?
The number of starting digits: Easy starts with 40, Medium with 32 and Hard with 26. With fewer numbers you need more logic.
What are notes?
They are small numbers you jot down in a cell to remember which ones can still go there. When you place a number, it is automatically removed from the notes in its row, column and box.
Can I continue a game later?
Yes. The game in progress is saved in your browser, and when you reopen the page you pick up where you left off.
Is it free? Do I need to install anything?
It is free, needs no sign-up and runs right in your browser, on a phone, tablet or computer.