1. Each row
Every horizontal row holds the digits 1 to 9, each exactly once. No repeats, none missing.
How to play Sudoku
To 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. No maths and no guessing, just logic: learn the rules, make your first move and finish an easy grid today.
How to play, step by step
- 1 Look at the grid: 81 cells arranged in nine rows, nine columns and nine 3×3 boxes (also called blocks or regions).
- 2 Find the clues. The numbers already printed, also called givens, are fixed and can't be changed.
- 3 Pick a digit, for example 5, and find a box that doesn't contain it yet.
- 4 Rule out every cell of that box whose row or column already holds a 5. If only one cell is left, the 5 goes there.
- 5 Repeat with other digits and boxes until every cell is filled and each row, column and box holds 1 to 9.
The goal
A Sudoku is a 9×9 grid split into nine 3×3 boxes. Some cells already hold a number; those are the clues. Your job is to fill every empty cell with a digit from 1 to 9. A well-made Sudoku has exactly one solution, and you can always reach it by logic alone. We have published a new Sudoku every day since 2005, in ten difficulty levels.
Sudoku rules
There are only three rules, and they all say the same thing about a different group of nine cells: each digit from 1 to 9 appears exactly once.
2. Each column
Every vertical column holds the digits 1 to 9, each exactly once.
3. Each 3×3 box
Every one of the nine 3×3 boxes, outlined with thicker lines, holds the digits 1 to 9, each exactly once.
How to solve a Sudoku: your first move
Pick a digit and look for the boxes that don't have it yet. Every row and column that already contains that digit rules out the cells it crosses. When only one cell of the box is left, the digit must go there.
When scanning runs out: pencil marks
On harder puzzles, scanning stops finding moves. Then write the possible digits, called candidates (also notes or pencil marks), small in the corner of each empty cell. Each time you place a digit, erase it from the candidates in its row, column and box. A cell left with a single candidate is solved.
Sudoku tips for beginners
- Start with the digit that already appears most often: it has the fewest places left to go.
- Scan the whole grid for one digit at a time instead of staring at a single cell.
- Look at boxes that are almost full first; they have the fewest options.
- Use a pencil on paper, or notes mode when you play online, so you can correct mistakes.
- Never guess. If you are stuck, go back to scanning: a move you missed is usually still there.
Common beginner mistakes
- Checking only the row or only the column. A digit has to fit its row, its column and its box at the same time.
- Guessing to get unstuck. One wrong guess can spoil the whole grid, and the error only shows up much later.
- Starting with a puzzle that is too hard. Begin with very easy or easy grids and move up when they feel quick.
Choosing a difficulty
Very easy and easy puzzles can be solved by scanning alone, which makes them perfect for learning. Medium adds pencil marks; hard and above need named techniques such as hidden pairs and the X-Wing. Every level has a new puzzle each day, to play online or print.
Ready to try?
Frequently asked questions
What are the 3 rules of Sudoku?
Each row, each column and each 3×3 box must contain the digits 1 to 9 exactly once. That's all: every solving trick is a consequence of these three rules.
What is the trick to solving Sudoku?
Scanning: take one digit at a time and find the only cell where it can go in a box, row or column. When that stops working, write candidates in the empty cells and look for cells with a single option.
Do you need to be good at maths to play Sudoku?
No. The digits are only symbols; you never add or multiply them. You could play with letters or colours and the logic would be the same.
Can you guess in Sudoku?
You never need to. A proper Sudoku has exactly one solution that logic alone can reach, and every puzzle on PrintSudoku is checked for that. A guess usually leads to an error you only discover much later.
Is Sudoku good for your brain?
It is a good workout for concentration, memory and logical thinking, which is why many people make it a daily habit. Like any puzzle it keeps your mind active, although it is not a medical treatment.