Killer Sudoku
A Sudoku grid with a twist: there are no starting digits. Instead, dashed cages tell you what their squares add up to, and digits never repeat inside a cage.
How to play Killer Sudoku
- As in classic Sudoku, every row, column and bold 3×3 box must contain the digits 1 to 9 once each.
- The grid is split into dashed cages. The small number in a cage’s corner is the total of the digits inside it.
- A digit can appear only once within a cage.
- Select a square to see its cage total and every set of digits that could make it in the helper under the board.
- Each puzzle is generated by our own code and has exactly one solution.
Controls
- Arrow keys: move 1–9: enter Shift + 1–9: note
- N: notes mode Backspace: erase Z: undo H: hint
Tips
- Every row, column and box adds up to 45. If cages cover a box except for one square sticking out, that square’s value is the difference.
- Some totals have only one way to be made: two squares adding to 3 must be 1 and 2, and three squares adding to 24 must be 7, 8 and 9.
- Crossed-out combinations in the helper conflict with digits you have already placed in that cage.
FAQ
How is this different from regular Sudoku?
The rules for rows, columns and boxes are the same, but you start from an empty grid and work out digits from the cage totals.
Are the puzzles guaranteed to have one answer?
Yes. Our generator checks every grid with a solver and keeps splitting cages until only one solution remains.
Is there a killer sudoku cheat sheet?
Yes: select any square and the helper under the board lists every digit set that fits its cage. These totals can only be made one way, so learn them first. 2 squares: 3 = 1+2, 4 = 1+3, 16 = 7+9, 17 = 8+9.
3 squares: 6 = 1+2+3, 7 = 1+2+4, 23 = 6+8+9, 24 = 7+8+9.
4 squares: 10 = 1+2+3+4, 11 = 1+2+3+5, 29 = 5+7+8+9, 30 = 6+7+8+9.
5 squares: 15 = 1+2+3+4+5, 16 = 1+2+3+4+6, 34 = 4+6+7+8+9, 35 = 5+6+7+8+9.
Also remember that every row, column and box adds up to 45.