Play sudoku online

Free sudoku in your browser

Play sudoku online for free, with nothing to install and no account. The puzzle starts as soon as the page loads, the clock stops when you pause or switch tabs, and your game is saved in this browser as you go, one game for each level, so you can come back to it later.

There are six levels, from Easy to Extreme, and 500 puzzles in each. Every puzzle has exactly one solution. The levels differ in the reasoning they need: Easy and Medium can be solved by finding the one cell where a number must go, while the harder levels need techniques such as locked candidates, pairs, the X-Wing and the XY-Wing. The level pages below explain what each one asks of you.

Notes, undo and erase work the way you would expect. When you get stuck, a hint finds the easiest next step, names the technique and explains why it works, so the hints teach as they help. Your statistics keep your best time, best score and win streak for each level.

Sudoku levels

• Easy sudoku: 36 to 40 numbers to start, singles only.
• Medium sudoku: 30 to 35 numbers to start, singles only.
• Hard sudoku: 26 to 31 numbers to start, locked candidates and pairs.
• Expert sudoku: 23 to 28 numbers to start, triples, quads and the X-Wing.
• Master sudoku: 22 to 27 numbers to start, wings and the Swordfish.
• Extreme sudoku: 21 to 26 numbers to start, beyond all of the above.

How to play

Fill the grid so that every row, every column and every 3 by 3 box holds the numbers 1 to 9 once each. Every puzzle has exactly one solution, and you can always reach it by logic, without guessing.

1. Select a cell, then tap a number. A wrong number turns red and counts as a mistake. Three mistakes end the game, but once per game you can take a second chance: the last mistake is removed and you carry on.
2. Turn on Notes to pencil in the numbers a cell could hold. When you place a number, it is removed from the notes in its row, column and box.
3. Undo takes back your last move, as many times as you like. Erase clears a wrong number or a cell’s notes. Numbers you placed correctly stay put.
4. Stuck? Hint shows the next step and explains it. Press it again to fill the cell.
5. The clock stops while you’re paused or in another tab. Your game is saved as you go, so you can come back to it later.
6. Settings lets you turn off the mistake check, the limit, the highlights or the timer. Statistics shows your wins, best times and streaks for each level.

Keyboard

Questions

What’s the difference between the levels?

Each level asks for harder reasoning. Easy (36 to 40 numbers to start) and Medium (30 to 35) only need you to find, again and again, the one cell where a number must go. Hard adds locked candidates and pairs, Expert triples and the X-Wing, and Master the Swordfish and the XY-Wing. Extreme puzzles need steps beyond all of these.

What does Hint do?

It finds the easiest next step on the board, names the technique and explains it, and highlights the cells and candidates involved. Press Hint again, or Apply, to fill the cell. A hint counts even if you fill the cell yourself, and that cell earns no points. If a number on the board is wrong, the hint points to it first.

How is the score worked out?

Each correct number earns points, more on harder levels and more the sooner it follows your last one. A number that completes a row, column or box earns five times as much for each one it completes. Hints earn nothing, and a cell only scores once, even if you undo it. With the mistake check turned off, there is no score.

Where is my game kept?

Only in this browser, one game per level, along with your statistics and settings. Nothing is sent anywhere, and clearing your browser’s site data removes them.

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