Sudoku Guide: How to Play, Rules, and Beginner Strategies

Sudoku looks intimidating at first — a 9x9 grid full of numbers — but the rules are simple enough to learn in two minutes. This guide walks you through everything you need to start solving your first puzzle today.

The Rules in 30 Seconds

• Fill the grid so every row, column, and 3x3 box contains the digits 1 through 9 exactly once.
• Some numbers are already filled in. These are your clues — you never change them.
• There is exactly one correct solution to every properly made puzzle.

That's it. No math, no addition, no language barrier. Sudoku is pure logic.

Reading the Grid

A standard sudoku has:

• 9 rows (numbered 1–9 from top to bottom)
• 9 columns (numbered 1–9 from left to right)
• 9 boxes (3x3 regions, sometimes drawn with thicker lines)

Every cell belongs to exactly one row, one column, and one box. A number can only appear once in each of those three groups. That single rule drives every solving technique there is.

Your First Technique: Scanning

Start by scanning the grid for rows, columns, or boxes that are nearly full. The fewer empty cells a group has, the easier it is to fill.

Example: if a row has 7 numbers already, only 2 digits are missing. Check which of those 2 digits already appear in the intersecting columns and boxes — often only one spot remains valid.

This process is called scanning, and it solves most easy puzzles on its own.

The Second Technique: Single Candidate

Pick an empty cell and ask: which numbers are not already in its row, column, or box? If only one number is possible, write it down. This is called a single candidate (or naked single).

Work through the grid cell by cell with this method, and easy and medium puzzles practically solve themselves.

Practice With Our Tools

The best way to learn is to play:

• Use the sudoku maker to generate puzzles at your chosen difficulty.
• Stuck on a puzzle? The hints tool on the homepage gives you the next logical step when you need a nudge.
• Prefer a bigger challenge? Try a mega sudoku 16x16 grid.

What's Next

Once scanning and single candidates feel natural, move on to sudoku logic for the deeper reasoning patterns, or jump straight into a step-by-step walkthrough of a full puzzle from first move to final cell.

Sudoku rewards patience — every puzzle is solvable with logic alone, no guessing required. Happy solving!