How to Play Sudoku: Beginner's Guide to the Logic Puzzle

Sudoku is the world's most popular logic puzzle. Learn the rules and master proven techniques to solve any puzzle.

Rules

Sudoku is played on a 9×9 grid divided into nine 3×3 boxes
Some cells are already filled in (these are called "givens")
Goal: Fill every empty cell with a number from 1 to 9
Each row must contain 1-9 exactly once
Each column must contain 1-9 exactly once
Each 3×3 box must contain 1-9 exactly once
No guessing required — every puzzle can be solved with logic

Basic Strategy: Scanning

The simplest technique is scanning rows and columns to find cells that can only have one possible number.

Example: If a row has 1,2,3,5,6,7,8,9, the missing number is 4. Find where 4 goes in that row by checking columns and boxes.

Intermediate Strategy: Cross-Hatching

Focus on one 3×3 box at a time. For each number 1-9:

Look at the rows and columns that pass through the box
Eliminate cells where the number can't go (because it already appears in that row/column)
If only one cell remains, that's where the number goes

Advanced Technique: Pencil Marks

When a cell has multiple possible candidates, write them down lightly (use the hint button in our game for assistance).

Example: A cell might be able to contain 3, 5, or 7. Write all three as pencil marks. As you solve other cells, you'll eliminate options until only one remains.

Common Mistakes

Guessing — Sudoku is pure logic. If you guess, you'll eventually get stuck.
Ignoring the 3×3 boxes — beginners focus only on rows/columns and forget the box constraint.
Not using pencil marks — trying to hold all possibilities in your head leads to mistakes.

Difficulty Levels

Easy (40 givens): Uses scanning + cross-hatching. Good for beginners.
Medium (30 givens): Requires pencil marks and some advanced techniques.
Hard (25 givens): Needs advanced logic and pattern recognition.

Benefits of Sudoku

Improves logical thinking — practice deduction and inference
Enhances concentration — requires sustained focus
Boosts working memory — track multiple possibilities
Reduces stress — focused problem-solving induces flow

Ready to Play?

Try these strategies in our free Sudoku game. It includes 3 difficulty levels, hints, and best time tracking.

For more tips, check out our Sudoku Tips guide.