Choose an Online Sudoku Difficulty
Every level uses the same Sudoku rules. The difference is how deeply you need to compare candidates and connect logical steps. Choose a puzzle that fits your experience and available time.
- Easy
- Find clear missing digits by scanning rows, columns, and 3 × 3 boxes. Easy Sudoku suits new players and short sessions.
- Medium
- Use candidate notes and compare several units before placing a digit. Medium puzzles introduce short chains of decisions.
- Hard
- Expect fewer direct placements and more interaction between candidates. Accurate notes and justified eliminations become more important.
- Expert
- Work through longer logical relationships without relying on guesses. Expert Sudoku rewards patient, methodical checking.
- Daily
- The Daily Sudoku provides one dated grid with a varying level, making it an easy way to build a regular solving habit.
How to Play Online Sudoku
Fill every empty cell with a digit from 1 to 9. Each digit may appear only once in every row, column, and 3 × 3 box. The original clues cannot be changed.
Start with a row, column, or box that is nearly complete. Record possible digits as notes, then place a number only when the current grid forces its position. If a move creates a duplicate, erase it and inspect the affected units again.
The game tracks time and mistakes, while pause, undo, erase, notes, and hints keep the board manageable. Hints explain a useful next step instead of replacing the whole solve.
Read the Complete Sudoku RulesSudoku Solver, Printable Puzzles, and Rules
Play, check, print, and learn from the same clear Sudoku grid instead of moving between unrelated tools.
Sudoku Solver
Enter clues, import the current board, or paste an 81-cell puzzle. The solver detects duplicate clues and distinguishes a unique solution, multiple solutions, and no solution.
Open the Sudoku SolverPrintable Sudoku Puzzles
Choose a difficulty and print the current puzzle for paper solving. The print layout keeps the level, puzzle ID, and 9 × 9 grid clear.
Print puzzles & answersIllustrated Sudoku Rules
Review rows, columns, boxes, legal moves, candidate notes, and conflict examples when learning the game or checking a disputed move.
View the Illustrated Sudoku RulesSudoku Strategy for Every Level
Reliable Sudoku strategy begins with facts already on the grid. Scan each row, column, and box, then keep only candidates that satisfy all three units.
Singles
Place a digit when a cell has one candidate, or when a digit has only one possible position within a row, column, or box.
Candidate Pairs
When two cells in one unit contain the same two candidates, remove those digits from the unit’s other cells.
Box-Line Interaction
If every candidate for a digit inside one box lies on the same row or column, remove it from the rest of that line outside the box.
Update related notes after every certain placement, then scan for singles again. Small, justified steps are usually faster and safer than guessing.