How to play Sudoku
A Sudoku grid has 81 cells arranged in 9 rows, 9 columns and nine 3x3 boxes. Some numbers are already given. Your goal is to fill every empty cell so that each row, each column and each 3x3 box contains the digits 1 to 9 exactly once. You never need to guess: every puzzle on this page is generated fresh in your browser and checked by a solver to make sure it has exactly one solution.
Tap or click a cell, then tap a number on the keypad (or type 1–9). Use Notes to write small pencil marks for candidates, Erase to clear a cell, and Undo to step back. Hint fills in the selected cell (or a random one) correctly, and Check highlights any wrong numbers. Keyboard: arrows move, N toggles notes, H gives a hint, P pauses.
Difficulty levels
Easy puzzles have about 40 given numbers and can be finished using only simple singles. Medium has about 32 clues and still needs no advanced tricks. Hard (around 27 clues) and Expert (around 24 clues) usually need pencil marks and more advanced reasoning. Your best time for each level is saved when you solve a puzzle without hints.
Sudoku tips for beginners
- Scan for singles. Look at one digit at a time and see where it can still go in each box.
- Look for the last empty cell. A row, column or box with eight numbers filled has only one choice left.
- Use notes on harder puzzles. Writing candidates makes pairs and hidden singles much easier to see. Correct entries remove matching notes automatically.
- Find naked pairs. If two cells in a unit can only be the same two digits, those digits can be removed from the other cells in that unit.
- Don't guess. If you are stuck, use a hint and study why that number fits.
A short history
The modern puzzle was first published in 1979 in an American puzzle magazine as "Number Place". It became popular in Japan in the 1980s under the name Sudoku, meaning roughly "single digits", and spread worldwide in 2004–2005 through newspapers. This page is a free, lightweight version with no sign-up; it works offline after the first visit and keeps your games and times only on your device.
FAQ
Is this Sudoku free?
Yes. It is free to play in any modern browser on phone, tablet or computer, with unlimited new puzzles.
Does every puzzle have one solution?
Yes. Each puzzle is checked by a solver while it is generated, and only puzzles with exactly one solution are shown.
Can I play Sudoku offline?
Yes. After the first visit the page is stored by your browser and works without an internet connection. Your current game is saved automatically.
What are notes or pencil marks?
Notes are small candidate numbers you write in a cell. Turn on Notes, then tap numbers to add or remove them.
Which level should I start with?
Start with Easy to learn the rules, move to Medium once you finish easily, and try Hard or Expert when you are comfortable with notes.