Every row must contain the numbers 1 to 9 exactly once
No number may appear twice in the same horizontal row. By the end, each row contains all digits from 1 to 9.
The 3 core rules
Sudoku rules explained in minutes so you can start playing right away. Includes solving tips and common beginner mistakes.
Every column must contain the numbers 1 to 9 exactly once
The same rule applies vertically. A digit may appear only once in each column.
Every 3x3 box must contain the numbers 1 to 9 exactly once
Each smaller box of nine cells also uses every digit only once. That is what makes Sudoku a logic puzzle rather than a math exercise.
A simple way to solve Sudoku
Start with easy areas
Look for rows, columns or 3x3 boxes that already contain many numbers. Those are often the quickest places to find the missing values.
Eliminate impossible numbers
For each empty cell, check which numbers already appear in the same row, column and box. Everything already used can be ruled out.
Only place certain numbers
Write in a number only when it is logically forced. Strong Sudoku play comes from certainty, not guessing.
Build from one sure step to the next
Every correct entry creates new information. That usually unlocks more cells elsewhere on the board.
Helpful beginner tips
- Start with the areas that are already the most complete.
- Always compare row, column and box together.
- Use notes when you are unsure instead of guessing.
- Change perspective often: a hard cell may become easy when you inspect its box.
Common mistakes
Guessing too early
A random guess often creates a chain of mistakes. It is usually better to wait for a fully logical move.
Ignoring the 3x3 box
Many beginners watch only rows and columns. The box is equally important and often gives the decisive clue.
Rushing through the scan
One missed number can block your entire line of reasoning. Slow, systematic checking is more effective than speed.
Questions about Sudoku rules
Do I need to be good at math to solve Sudoku?
No. The numbers act like symbols. Sudoku is about logic and pattern recognition, not calculation.
Should I guess if I get stuck?
It is better not to. A well-made Sudoku can be solved logically without random guessing.
Which difficulty should I start with?
Easy Sudoku is the best starting point because the rules and patterns are easier to see.