Sudoku Online
Challenge your brain with our free Sudoku puzzles. Choose your difficulty and start playing!
How to Play Sudoku
1. The Grid
Sudoku is played on a 9x9 grid divided into nine 3x3 boxes.
2. The Goal
Fill every row, column, and 3x3 box with numbers 1-9 without repeating.
3. The Rules
Each number 1-9 can only appear once in each row, column, and box.
4. Strategy
Use logic and elimination to find the correct numbers for each cell.
Difficulty Levels
Start with rows, columns, or boxes that have the most numbers already filled in. This makes it easier to identify which numbers are missing.
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Frequently Asked Questions
How do I play Sudoku?
Click on an empty cell and enter a number 1-9 using your keyboard or the on-screen number pad. The goal is to fill every row, column, and 3x3 box with numbers 1-9 without repeating any number. Pre-filled numbers (given clues) cannot be changed.
What do the difficulty levels mean?
Easy puzzles have 38+ cells pre-filled, Medium has 30-37 cells, and Hard has only 22-29 cells filled. Fewer clues means more logical deduction is required. Each difficulty also has different mistake limits: Easy allows 20, Medium allows 15, and Hard allows only 10 mistakes.
What do the Hint and Undo buttons do?
The "Hint" button reveals the correct number for the currently selected cell, helping when you're stuck. The "Undo" button removes your last entry, letting you correct mistakes. Use hints sparingly for the best solving experience!
Can I download puzzles to print?
Yes! Click the "Download PDF" button to generate a printable PDF with two pages: the puzzle on page one and the complete answer key on page two. Perfect for offline solving, classroom activities, or sharing with friends.
Is Sudoku good for the brain?
Absolutely! Sudoku is an excellent brain exercise that improves logical thinking, concentration, pattern recognition, and short-term memory. Regular puzzle-solving has been linked to better cognitive function and may help keep the mind sharp at any age.
What happens if I make too many mistakes?
Each difficulty level has a mistake limit. If you exceed it, the game ends and you'll need to start a new puzzle. Mistakes are tracked in real-time, so watch the counter carefully. Use the Undo button or Hints to avoid running out of attempts!