How to Play Sudoku Online

Know the goal

Complete the 9×9 grid so every row, every column and every 3×3 box contains digits 1 through 9 without repeats. The starting numbers are fixed clues. Every empty cell must be solved through elimination and pattern recognition.

Choose a difficulty

Easy offers more direct placements, while Medium requires more repeated scanning. Hard and Expert reduce the number of obvious moves and make candidate notes more useful. If you are new, learn on Easy before trying to solve against the timer.

Use the online controls

• Select an empty cell with a tap, click or arrow key.
• Enter a digit with the on-screen number pad or keyboard.
• Turn on Notes when several candidates remain.
• Use Undo or Erase to correct an entry.
• Use a hint only after checking the connected row, column and box.

Build a solving rhythm

Start with nearly complete units, then scan one digit across the whole grid. When progress slows, compare candidates instead of guessing. A correct online solve follows the same logic as a paper puzzle; the interface simply makes input and feedback faster.

Continue with the beginner walkthrough or compare Sudoku difficulty levels.