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How to Play Sudoku: The Complete Beginner’s Guide
Sudoku has only one rule, and you can learn it in a minute. Getting good at it takes a little longer, and that is the fun part. This guide covers everything you need for your very first puzzle.
The grid
A Sudoku grid is a big square made of 81 small squares, called cells. The cells are arranged in 9 rows (left to right) and 9 columns (top to bottom). Thick lines also divide the grid into 9 smaller 3×3 squares, called boxes.
Some cells already have numbers in them. These are the givens or clues, and they never change. Your job is to fill in all the empty cells.
The one rule
Every row, every column and every 3×3 box must contain each number from 1 to 9 exactly once.
That is all. No number can repeat in a row, in a column or in a box. Because there are 9 cells in each and 9 numbers to place, every number appears exactly once in each of them.
Every puzzle has one answer
A well-made Sudoku has exactly one correct solution. That means you never need to guess. At every step, there is a cell that logic alone can fill. If you find yourself guessing, it simply means there is a clue you have not spotted yet.
Your first moves
- Pick a number. Start with a number that already appears many times in the grid, for example 5.
- Look at one box. Find a 3×3 box that does not have a 5 yet.
- Cross out the impossible cells. If a row or column passing through that box already contains a 5, no cell of that row or column inside the box can be a 5.
- Find the last spot. If only one empty cell is left in the box, the 5 must go there. Write it in.
- Repeat. Try the same number in the next box, then move to the next number.
This simple method is called scanning, and it solves a large part of every easy puzzle. Read our guide to scanning to master it.
When you get stuck
Sooner or later scanning will stop finding new numbers. That is when you start writing small pencil marks: the possible numbers for each cell. From there, solving becomes a game of elimination. Our pencil marks guide shows you how.
Quick summary
- 81 cells, 9 rows, 9 columns, 9 boxes.
- Each row, column and box holds 1 to 9 once.
- No math and no guessing, only logic.
- Start by scanning one number at a time.
Ready? The best way to learn is to play. Start with an Easy puzzle and remember: every cell you fill makes the next one easier.