Sudoku online: free puzzles

Choose your level

• Easy sudoku: solvable by looking for the only possible number.
• Medium sudoku: adds pairs and pointing candidates.
• Hard sudoku: adds hidden pairs and box-line reductions.
• Expert sudoku: needs an X-Wing or a Swordfish somewhere along the way.

The rules in one minute

Fill the grid so that every row, every column and every 3×3 box holds each number from 1 to 9 exactly once. The numbers already on the board can't be changed. Each puzzle has exactly one solution, and you never need to guess. There's a longer walkthrough in how to play sudoku.

How levels are graded

A puzzle's level comes from the hardest technique it actually requires, not from how many numbers it starts with. A solver works through each board using the same logic a person would, and the board is labeled by the simplest set of techniques that finishes it. See the full list in sudoku techniques.

Handy controls

Use the number pad or your keyboard to fill a cell. Arrow keys move around the board, and Pencil notes down candidates. You get three hints per puzzle, and your game saves after every move, so you can pick it up later on this device. Prefer paper? Open printable sudoku.