Learn Sudoku
Everything you need to go from your first puzzle to Expert level: the rules, how to think about a grid, and each solving technique shown on a real position.
Play, solve and print
- Play Sudoku onlineA clean board with notes, undo and hints that teach.
- Daily SudokuOne new puzzle every day, free in your browser.
- Sudoku solverGet the answer, or learn the next logical step.
- Printable SudokuFree sets at five levels, with an answer page.
- Easy SudokuSingles only. The gentlest way to start.
- Medium SudokuPairs and pointing pairs on top of singles.
- Hard SudokuTriples and careful notes. A real challenge.
- Expert SudokuX-Wing and Swordfish patterns across the grid.
- Extreme SudokuXY-Wing and coloring. Only for serious solvers.
The basics
- How to play SudokuThe grid, the one rule and your first move.
- Sudoku rulesEvery rule, what breaks it and what makes a puzzle valid.
- Sudoku for beginnersA simple five-step plan from first puzzle to Medium.
- Sudoku difficulty levelsWhat each level needs, by technique.
- Sudoku FAQQuick answers to the questions people ask most.
- Sudoku glossaryThe vocabulary of Sudoku in plain language.
Strategy
- How to solve SudokuA repeatable method from first digit to last.
- Sudoku tips and tricksFifteen habits that make solving faster and calmer.
- Notes and pencil marksWhen to write candidates and how to keep them clean.
- Sudoku techniquesAll twelve techniques, from easiest to hardest.
- How Sudoku hints should workUse hints to learn the pattern, not to skip it.
- Why a Sudoku has one solutionUniqueness, the 17-clue minimum and how many grids exist.
Solving techniques
- Naked singleA cell that has only one possible digit left.
- Hidden singleA digit that has only one place left in a unit.
- Naked pairTwo cells that share the same two candidates.
- Hidden pairTwo digits that fit in only the same two cells.
- Pointing pairsA digit in a box that sits on one line.
- Box-line reductionA digit in a row or column confined to one box.
- Naked tripleThree cells that share only three candidates.
- Hidden tripleThree digits that fit in only three cells.
- X-WingA digit locked into the same two lines across two rows.
- SwordfishThe X-Wing idea, across three rows and columns.
- XY-WingThree two-candidate cells that eliminate a digit.
- Simple coloringFollow one digit through a chain of two colors.
More about Sudoku
- Killer Sudoku rulesSudoku with cages and target sums instead of givens.
- History of SudokuFrom Number Place to a worldwide puzzle.
- Is Sudoku good for your brain?An honest look at what the research shows.
- Sudoku app for AndroidOur Android app with graded levels and teaching hints.
- How our puzzles are madeOne solution, solvable by logic, graded by technique.