Featured: ChessPlay Sudoku Online Free
Classic 9x9 Sudoku with a new daily puzzle, unlimited free play, notes, hints and undo. Your game saves automatically, and you can race friends live.
How to play Sudoku
New to Sudoku? Read the tips and strategies guideScanning, pencil marks, naked pairs, pointing pairs and the X Wing, with diagrams.Pick a puzzle
Play the Daily Sudoku, start a free play puzzle, or create a room to race friends. Choose Easy, Medium, Hard or Expert.
Select a cell
Tap or click an empty square. Its row, column and 3x3 box light up, and every matching number is highlighted.
Place a number
Tap 1 to 9 on the pad or type it. Wrong numbers turn red and add to your mistake count, so think first.
Fill the grid
Finish when every row, column and box holds 1 to 9 exactly once. Your time and mistakes are saved.
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Sudoku rules
A Sudoku grid has 81 squares arranged in nine rows, nine columns and nine 3x3 boxes. Some squares start with a number, called a clue or given. Your job is to fill every empty square with a digit from 1 to 9 so that no digit repeats in any row, any column or any box.
Every puzzle on this page is checked by a solver to have exactly one solution, so you never need to guess. A correct Sudoku can always be solved by logic alone. When you place a wrong number it turns red and the mistake counter goes up by one. The game never ends because of mistakes, but a clean solve with zero mistakes is something to be proud of.
The small number on each pad key shows how many of that digit you still need to place. When a row, column or box is complete and correct it flashes green.
Levels explained
| Level | What to expect |
|---|---|
| Easy | 36 to 45 clues. Solvable with singles only: look for the one place a number can go. |
| Medium | 30 to 35 clues. Needs pointing pairs, box line reduction and naked pairs. |
| Hard | 26 to 31 clues. Adds hidden pairs, triples and sometimes an X wing. |
| Expert | 22 to 27 clues. Swordfish, XY wings and coloring chains appear. |
Your best time for each level and your daily streak are saved on this device.
Game modes and tools
Daily Sudoku and streak
Each day brings four new daily puzzles, one per level, and everyone in the world gets the same ones. The puzzles change at midnight UTC and the home screen shows how long until the next one. Solve at least one daily puzzle every day to grow your streak. Miss a day and the streak starts again from one.
Free play
Free play gives you a brand new puzzle at the level you choose, as often as you like. Your best time per level is shown on the level buttons.
Race friends live
Choose Race friends, enter your name and create a room, then share the six character code or the invite link with up to three friends. The host picks the level and everyone gets exactly the same puzzle after a short countdown. Live progress bars show how many correct squares each player has filled and how many mistakes they made. The host's game checks every number, so nobody can fake a finish. The first player to complete the grid correctly wins, and everyone sees the final standings. Hints are off in a race, and the host can start a rematch with one tap.
Notes, hints, undo and autosave
Turn on Notes to pencil small candidate numbers into a square. You get three hints per solo puzzle: a hint fills the selected square, or a random empty one, with the correct digit. Undo steps back one move at a time and Erase clears a square. Your solo game saves after every move, so you can close the tab and press Continue later. The timer only runs while the page is open in front of you.
Sudoku tips and strategies
Start with scanning. Pick a digit that appears many times, say 7, and check each box without a 7. The 7s in nearby rows and columns block most squares in that box, and often only one square is left.
Next, look at single squares. If a row, column and box together already contain eight different digits, the last one must go in that square. On harder levels use Notes to write the candidates for each square in a box or row, then look for patterns.
A naked pair is two squares in the same unit that can only hold the same two digits. Those two digits must go there, so you can remove them from every other square in that unit. A pointing pair is a digit that can only sit in one row inside a box, which removes it from the rest of that row. The X wing and swordfish extend the same idea across two or three rows and columns.
Finally, slow down to go fast. If you are not sure, write a note instead of a guess.
Why play Sudoku
Sudoku is a calm way to train focus, working memory and logical reasoning. A daily puzzle is a healthy habit, and racing friends makes it social. No math is needed, the digits are just symbols, so players of every age can enjoy it.
Sudoku FAQ
Is this Sudoku free to play online?
Yes. Sudoku on OnlineGames2Play is completely free and runs in your browser on any phone, tablet or computer. There is nothing to download, no account and no sign up.
What are the rules of Sudoku?
Fill every empty square of the 9x9 grid with a digit from 1 to 9 so that each row, each column and each 3x3 box contains every digit exactly once. The starting numbers cannot be changed.
Does every puzzle have only one solution?
Yes. Every puzzle is checked by a solver before you see it and has exactly one correct solution, so it can always be solved with logic and no guessing.
How does the Daily Sudoku streak work?
There are four daily puzzles each day, one per level, and they are the same for everyone. Solve at least one of them every day to grow your streak. New puzzles arrive at midnight UTC.
What happens when I make a mistake?
A wrong number turns red and your mistake counter goes up by one. Each wrong number is counted once per square. The game never ends because of mistakes, so you can always finish the puzzle.
How do notes and hints work?
Turn on Notes to write small candidate numbers in a square. In solo games you get three hints per puzzle, and each hint fills one square with the correct digit. Undo steps back one move at a time.
Can I play Sudoku with friends?
Yes. Choose Race friends, create a room and share the code or invite link with up to three friends. Everyone gets the same puzzle, live progress bars show how far each player is, and the first correct complete grid wins.
Is my game saved if I close the page?
Yes. Your solo game saves on this device after every move. Come back later and press Continue to pick up where you left off, with the same time, notes and mistakes.
More puzzle and party games
See all free puzzle games, read our Sudoku tips and strategies guide, or browse more tips on the OnlineGames2Play blog.