How to play sudoku
The goal is to fill the board so that every row, every column and every box contains each number exactly once. Classic 9×9 sudoku uses the numbers 1 to 9 and is divided into nine 3×3 boxes.
Select a cell and type a number using the on-screen keypad or your keyboard. Turn on notes mode to pencil in small candidates while you reason. If you get stuck, a hint shows you the next logical step and explains why.
Difficulty levels
- Easy
- Plenty of starting clues. Just find cells where only one number fits.
- Medium
- Fewer clues. Sometimes you'll need locked candidates inside a box.
- Hard
- Requires naked or hidden pairs and triples, plus locked candidates.
- Expert
- Demands advanced techniques such as X-Wing, Y-Wing or Swordfish, yet is always solvable with logic, no guessing.
Board sizes
Besides classic 9×9 sudoku you can play 4×4 and 6×6 mini sudokus, great for kids and beginners, an 8×8 with 2×4 boxes, and a giant 12×12 sudoku that uses the letters A, B and C for the values 10, 11 and 12.
Features that help you play
- Highlight duplicate numbers in a row, column or box.
- Show mistakes by checking against the solution.
- Manual notes and auto notes with every candidate.
- Hints that explain the technique: single candidate or single possible spot.
- Unlimited undo, a pausable timer and personal bests.
- Your game is saved in the browser, so you can close the tab and continue later.
- Dark mode and a layout that works on phone, tablet and desktop.