How to Play Sudoku

Sudoku is a logic puzzle you solve with reasoning, not luck — and you can learn the whole game in a few minutes. Here are the rules, how to read the grid, and the first moves that crack any puzzle.

The goal

Fill the 9×9 grid so that every row, every column, and every 3×3 box contains the digits 1 to 9, with no repeats. Every puzzle starts with some digits already placed, and there is always exactly one solution you can reach by pure logic — you never have to guess.

A Sudoku grid with one 3×3 box highlighted537619598686348317266284195879
A Sudoku grid. The highlighted 3×3 box — like every row and every column — must hold the digits 1–9 exactly once.

The only rule

There is really just one rule, applied three ways: a digit can’t repeat in a row, a column, or a 3×3 box. That’s it. You don’t add or calculate anything — the digits 1–9 are just nine symbols, so no math is involved.

Your first move: the naked single

The simplest move is to find a cell that can only be one digit. Look at the highlighted cell below. Its row already contains 1, 2, 3 and 4; its column contains 5, 6 and 7; and its box contains 8. That’s eight of the nine digits — so the only digit left for this cell is 9. A cell with just one possible digit is called a naked single.

Naked single worked example: the highlighted cell must be 9567812349
Every digit except 9 already appears in this cell’s row, column, or box — so it must be 9.

Placing that 9 removes it as an option from the rest of its row, column and box — which often creates the next naked single. Solving a Sudoku is mostly a chain of these small deductions.

How to solve Sudoku, step by step

Start easy and add techniques as puzzles get harder. This is the order most solvers learn — each links to a free, step-by-step lesson:

  1. Naked singles — a cell with only one possible digit.
  2. Hidden singles — a digit that fits only one cell in a row, column, or box.
  3. Naked pairs — two cells sharing the same two candidates — eliminate those digits elsewhere.
  4. Pointing pairs — a candidate confined to one line within a box points along that line.
  5. Box/line reduction — a candidate confined to one line inside a box clears the rest of the box.
  6. X-Wing — a rectangle pattern that eliminates a candidate across two lines.

Easy puzzles need only the first one or two. As you climb to Hard and Expert, the later patterns become essential.

Play a free puzzle See all techniques

Frequently asked questions

How do you play Sudoku?

Fill the 9×9 grid so that every row, every column, and every 3×3 box contains the digits 1 to 9 exactly once. You start from the given digits and use logic — never guessing — to work out the rest.

What are the rules of Sudoku?

There is only one rule: no digit may repeat within a row, a column, or a 3×3 box. A correct Sudoku has exactly one solution reachable by logic.

How do I solve a Sudoku for beginners?

Scan for cells that can only be one digit (a "naked single") or a digit that fits only one cell in a row, column, or box (a "hidden single"). Place those, then repeat — the grid opens up as you go.

Do you need math to play Sudoku?

No. Sudoku uses the digits 1–9 as symbols, not for arithmetic — it is pure pattern logic. You never add, subtract, or calculate anything.

How do I get better at Sudoku?

Learn the solving techniques in order — singles, then pairs and pointing pairs, then patterns like the X-Wing. Each technique unlocks harder puzzles. Our free step-by-step lessons teach them one at a time.