The art of paying attention

How to play Sudoku

A few simple rules. A satisfying world of possibilities.

The goal

Fill the 9 × 9 grid with the numbers 1 through 9. Each row, each column, and each of the nine 3 × 3 boxes must contain every number exactly once. The starting numbers stay fixed.

Start with what you know

Look at a nearly filled row, column, or box. Which numbers are missing? Scan the crossing rows and columns to narrow down where each number can go. Sometimes a cell has only one possibility; sometimes a number has only one place inside a unit.

Keep a pencil nearby

Choose Easy for a gentler start, Medium for hidden singles, Hard for locked candidates and pairs, or Expert for puzzles beyond those techniques.

Turn on Notes to record possibilities in an empty cell. Notes are yours to manage; Sudoku does not fill them automatically. As you learn more, remove possibilities that no longer fit.

Killer Sudoku: follow the totals

Killer uses the same row, column, and box rules, with dashed cages. Each cage adds up to the small total in its corner, and digits cannot repeat within a cage. A cage containing just one square tells you its digit. Cage totals provide the starting clues instead of fixed numbers.

Try an Easy Killer puzzle →

Use the keyboard

Arrow keys move around the grid. Press 1–9 to enter a number, Backspace or Delete to clear a cell, and N to toggle notes. Ctrl/⌘ + Z undoes a move; Ctrl/⌘ + Shift + Z redoes it. Tab moves between the board and controls.

Give yourself time

Every puzzle has one solution. There are no hints, auto-solve, or answer-checking tools. Classic highlighting flags repeated numbers. Killer also flags repeated cage digits and totals that are exceeded or incorrect when a cage is filled. Both are optional. Your current puzzle saves in this browser so you can return to it.