Sudoku for Beginners: How to Read a Sudoku Grid

Sudoku looks more complicated than it is. The grid is large, the numbers are many, and the empty squares can feel intimidating. But the rule is just one sentence long, and reading the grid becomes automatic after a few minutes.

The one rule of Sudoku

Every row, every column, and every 3×3 box must contain the digits 1 through 9 exactly once.

That's it. No math. No arithmetic. No hidden patterns. Just placement.

How the grid is organized

A standard Sudoku grid is 9×9, divided into:

- **Rows** — nine horizontal lines - **Columns** — nine vertical lines - **Boxes** — nine 3×3 blocks

Each row, column, and box is a "house." A number can only appear once in each house.

How to read a given puzzle

Start by scanning for the most common given numbers. If a row already has five numbers filled in, only four digits are missing — and the empty cells are heavily constrained. The same logic applies to columns and boxes.

Your first move: look for a number that is almost complete

Pick a digit, say 3, and scan each 3×3 box. If a box already has two 3s visible in nearby boxes, the third 3's location is often forced. This is the easiest way for beginners to make progress without memorizing complex techniques.

What the difficulty levels mean

- **Easy** puzzles can usually be solved by scanning and single-candidate cells - **Medium** puzzles require you to track candidates in each cell - **Hard** and **Expert** puzzles need advanced techniques like pairs, triples, and X-Wing

Puzzle Theory Sudoku offers four difficulties, including a gentle daily puzzle for beginners.

Practice on a real board

The fastest way to learn is to play. Start with an easy puzzle, use the notes feature if you get stuck, and don't worry about speed. For more advanced solving, see our Sudoku solving techniques guide.