Sudoku

About Sudoku

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, so it can always be solved by reasoning alone; you never have to guess. Medium boards count for the weekly leaderboard, which resets every Monday at 00:00 UTC. Easy and Hard are there for warming up and for a challenge, and are not ranked.

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.
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 weekly 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.

Questions players ask