How to Play Sudoku
Sudoku looks intimidating, but the rules are simple. Here is everything a beginner needs, plus tips to get faster — then try it free below.
The Rules of Sudoku
A sudoku board is a 9 by 9 grid, divided into nine 3 by 3 boxes. Your goal is to fill every empty cell with a number from 1 to 9 so that:
- Every row contains 1 to 9 exactly once.
- Every column contains 1 to 9 exactly once.
- Every 3 by 3 box contains 1 to 9 exactly once.
Some numbers are already filled in at the start — these are the givens, and they never change. A well-made puzzle has exactly one solution. You never need to guess; every move can be worked out with logic.
Easy Techniques for Beginners
1. Scan rows and columns
Pick a number, say 1. Look at each row, column and box that already contains a 1 — the remaining empty box must hold the last 1. Cross out impossible cells until only one cell is left.
2. Use the "only one spot" trick
Inside any 3 by 3 box, if a number can only go in one empty cell, place it there. This single-cell placement is the most common beginner technique.
3. Pencil in candidates
In each empty cell, lightly note which numbers are still possible. Cells with just one candidate are solved for free.
Tips to Get Better
- Start easy: our Easy level is perfect for learning the rules.
- Work in pencil: write candidates in every cell before deciding.
- Use the Note mode in our sudoku game to keep candidates tidy.
- Stuck? Use the Hint button to reveal the next correct number.
- Move up to Medium, Hard and Expert as you improve.
Ready? Play sudoku online free right now — no download, and your progress is saved as you go.
Frequently Asked Questions
What are the rules of sudoku?
Fill the 9x9 grid so that every row, every column and every 3x3 box contains the digits 1 to 9 exactly once. Some numbers are given at the start and never change.
Do you need to guess in sudoku?
No. Every properly made puzzle has exactly one solution and can be solved using logic alone — scanning rows and columns, and placing numbers where only one spot fits.
Is sudoku hard for beginners?
Not at all. Start on Easy difficulty, use pencil marks for candidate numbers, and use hints when you are stuck. Most people learn the rules in under five minutes.
Can I play sudoku online for free?
Yes. PlayArcade sudoku is free with four difficulty levels, note mode and hints — playable in any browser with no download.