Play Classic Sudoku Online Free

Play Classic 9×9 Sudoku online for free. Fill the grid so every row, column, and 3×3 box contains digits 1-9. Multiple difficulty levels from easy to extreme.

▶ Play Classic Sudoku — Free

🟢 Easy 🟡 Medium 🟠 Hard 🔴 Expert

How to Play Classic Sudoku

Fill every row with digits 1 through 9, no repeats.
Fill every column with digits 1 through 9, no repeats.
Fill every 3×3 box with digits 1 through 9, no repeats.
Use logic — no guessing needed for a well-crafted puzzle.

💡 Pro Tip

Start by scanning for rows, columns, or boxes with only one missing digit. Use pencil marks to track candidates.

Frequently Asked Questions

How many valid Sudoku puzzles exist?

There are approximately 6.67 sextillion (6.67 × 10²¹) valid completed Sudoku grids.

What's the minimum number of clues for a unique Sudoku?

17 clues is the proven minimum for a standard 9×9 Sudoku with a unique solution.

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