Sudoku

About Sudoku

The classic 9×9 number puzzle, with a monthly leaderboard for the fastest clean solves.

Sudoku is a placement puzzle: a 9×9 grid split into nine 3×3 boxes, with some numbers already filled in. Your job is to complete the grid so that every row, every column and every box contains the digits 1 to 9 exactly once. There is no arithmetic involved — the digits could just as well be colours or letters. What matters is where each one can and cannot go.

Every board here is generated fresh and checked to have exactly one solution. That check rules out ambiguous completions; it does not promise that a beginner technique will settle every cell. Medium boards count for the monthly leaderboard, which resets on the 1st of every month at 00:00 UTC. Easy and Hard are there for warming up and for a challenge, and are not ranked.

On a phone, select a cell and use the number pad. On a keyboard, use the arrow keys and digits; N switches pencil notes on or off. Start by scanning one digit across the boxes, then look for a row or column with only one missing number. Notes let you record possibilities without committing a digit. A wrong entry counts as a mistake and three mistakes end the board, so a justified placement is more useful than a quick guess.

How to play

1. Pick a level. Medium is the ranked level; Easy and Hard are for practice.
2. Select an empty cell, then tap a number on the pad or type it on your keyboard. Arrow keys move between cells. Switch Notes on (or press N) to pencil in the numbers a cell could still take; notes never count as mistakes.
3. Each digit must appear once in its row, its column and its 3×3 box. A wrong digit shows in red and counts as a mistake.
4. Three mistakes end the board. Erase with ⌫, Backspace or Delete.
5. Fill every cell correctly to finish. Your time is measured by our server from the moment the board is dealt.
6. Sign in to put your time on the monthly leaderboard and keep your progress across devices. You can play without an account.

Tips

• Scan one digit at a time across the whole grid. Looking for every place a 7 could go is faster than staring at one cell.
• When a digit can go in only one cell of a row, column or box, it must go there — even if that cell could also hold other digits.
• If two cells in a box can only hold the same two digits, those digits are used up for the rest of that box. Cross them off elsewhere.
• Tapping a filled cell highlights every matching digit, which makes the gaps for that digit easy to spot.
• Speed comes from not making mistakes. A careful pass that never needs an eraser beats a fast one that does.

Guides

• Sudoku strategies: from the first scan to pairs and pointing

Questions players ask