Hard Sudoku
Free hard Sudoku puzzles
Keyboard: arrows move, 1–9 fill, Backspace erases, N toggles notes, Z undoes. Best times:
About Hard Sudoku
Hard Sudoku puzzles start with about 27 clues. You'll need to pencil in candidates with Notes and use techniques like naked pairs and pointing pairs, but every puzzle can still be solved by logic alone. New puzzles are generated endlessly in your browser and your game is saved if you leave.
- Pick a difficulty.
- Select a cell and tap a number (or type 1–9). Turn on Notes to pencil in candidates.
- Fill every row, column and box with 1–9 to win. Use Hint or Undo if you get stuck.
Frequently asked
How many clues does hard Sudoku have?
About 27 of the 81 squares are filled in at the start.
Can I get a hint?
Yes. Press Hint to fill in the selected square (or a random one). Games solved with hints don't count towards your best time.
Are the puzzles different every time?
Yes. A new puzzle is generated for each game, and each one is checked to have exactly one solution.
Is what I type sent to a server?
No. The tool runs entirely in your browser and there's no server behind it, so what you type never leaves your device and nothing is stored. You can check: it keeps working if you go offline after the page has loaded.
More from the Games drawer
Other tools kept in this drawer, plus a few favourites from the bench.