Hard Sudoku
HardHard Sudoku trims the clues further. Look for hidden singles and box-line interactions before placing digits.
Time0:00
Difficulty
Mistakes: 0
How to play
Click or tap a cell, then enter a digit. Use Notes for pencil marks. On desktop, arrow keys move the selection; press N to toggle notes.
Tips & more
What is Sudoku?
Sudoku is a logic puzzle on a 9×9 grid divided into nine 3×3 boxes. Each row, column, and box must contain the digits 1 through 9 exactly once. No arithmetic is required—only deduction.
How to play
- Scan for obvious singles—cells where only one digit fits.
- Use notes to track candidates when several digits might work.
- Check the row, column, and box together before committing a number.
- Reset restores the original puzzle; New puzzle shuffles a fresh grid.
Hard Sudoku tips
When the grid feels stuck, revisit boxes with only one or two empty cells. Pointing pairs from a box into a row can unlock the next placement.
Word tools
Need a break from numbers? Try the word unscrambler or anagram solver.
More Sudoku pages
- Sudoku home
- Easy
- Medium
- Hard (this page)
- Expert
- Daily