How to play sudoku
- Fill the 9×9 grid so that every row, every column and every 3×3 box (outlined in bold) contains each number from 1 to 9 exactly once.
- Tap a cell, then tap one of the number keys below the board. On a keyboard, just type 1–9.
- Not sure yet? Turn on Notes and pencil in the candidates. When you place a number, that note disappears from the same row, column and box automatically.
- Stuck? Tap Hint: the game shows the next logical step and explains why. Undo is always one tap away.
- Tap New game to pick Easy, Medium, Hard or Expert, or to open the daily puzzle.
Online sudoku with a fresh, unique puzzle every time
Sudoku needs nine digits and a little logic, not arithmetic. The puzzles here don’t come from a fixed list: each new game is generated from scratch in your browser. The generator first builds a valid, completely filled grid, then removes numbers in symmetric pairs and checks after every step that the puzzle still has exactly one solution. You will never get a puzzle with two right answers or one that forces you to guess.
How difficulty is decided
Difficulty isn’t just a count of empty cells. Every puzzle is graded by solving it the way a person would. Easy and Medium puzzles fall to naked and hidden singles alone; Medium starts with fewer clues. Hard puzzles need at least one elimination such as locked candidates or a candidate pair. Expert puzzles call for advanced techniques like the X-Wing, the XY-Wing or triples. At every level the solution can be reached by logic.
Notes and hints
On harder puzzles it helps to pencil in the candidates for each cell, just like solving on paper. In Notes mode, tapping a number adds or removes it; on a keyboard, hold Shift while typing a number. “Fill in all notes” in Settings writes every candidate in one tap. A hint doesn’t simply give the answer away: if you have entered a wrong number it points that out first; otherwise it finds the next easy step, highlights the row, column or box involved and explains it in a short sentence such as “7 fits nowhere else in this box”.
Mistakes, highlighting and the timer
With “Show mistakes right away” on, a wrong number turns red and is added to the mistake counter; switch it off if you’d rather test yourself. The row, column and box of the selected cell are shaded and matching numbers stand out. Completing a row, column or box sends a short wave across it. The timer runs at the top and the game pauses itself when you switch to another tab.
Daily puzzle and statistics
Everyone gets the same daily puzzle each day; its difficulty depends on the day of the week, with tougher puzzles at the weekend. Solve it on consecutive days to grow your streak. For every level you can see how many puzzles you have solved and your best and average times. All of this is stored only in this browser on this device; no account is needed and nothing is sent to a server.
Three tips for beginners
- Start with the number that appears most often and scan the boxes where it is still missing.
- If a row, column or box has only one empty cell, the missing number is easy to spot.
- Don’t guess: every puzzle has one solution that logic can reach.
Frequently asked questions
Is this sudoku free?
Yes. You can solve as many puzzles as you like without signing up or downloading anything. It runs in the browser on phones, tablets and computers.
Does every puzzle have only one solution?
Yes. Each puzzle is checked for a unique solution while it is generated, and it can be solved with logical steps, without guessing.
What is the difference between the levels?
Easy and Medium puzzles can be solved with naked and hidden singles; Medium starts with fewer clues. Hard puzzles need eliminations such as locked candidates and pairs, and Expert puzzles need advanced techniques such as the X-Wing and XY-Wing.
What is the daily puzzle?
It is one puzzle that is the same for everyone on a given day. Its difficulty changes with the day of the week. Solve it on consecutive days to build your daily streak.
Is my game saved if I close the page?
Yes. Your puzzle in progress, notes, settings and statistics are stored in this browser on this device. When you come back the game opens paused and you carry on where you left off.