1. The normal rules still apply
Every digit from 1 to 9 appears exactly once in each row, column and 3 by 3 box — just like classic sudoku.
Play killer sudoku
Killer sudoku is the classic sudoku with an extra layer: the grid is divided into cages with a sum label. The digits in each cage must add up to exactly that total — and no digit repeats within a cage. Easy gives you starting digits; on Expert the grid starts almost empty and the sums carry you through — four levels, each with a guaranteed unique solution.
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How killer sudoku works
2. Cages with a sum
The dashed lines divide the grid into cages. The small number in the top-left corner is the sum of the digits in that cage — and no digit repeats within a cage.
3. Start with the small cages
A two-cell cage with sum 3 can only be 1+2; sum 17 only 8+9. Those cages are your entry point — the rest fills in step by step.
Every puzzle has a valid solution and the error check also looks at the cages. Stuck? The hint button fills in a correct digit — no penalty, just like all our puzzles.
More killer sudoku
Daily Killer Sudoku
One killer every day, the same for everyone. Build your streak — separate from your regular sudoku streak.
Play today's killerPrefer classic?
The regular sudoku, from easy to hard, with a daily puzzle and a print version.
Go to classic sudokuRules and solving tips
How do the cages work and where do you start? The rules in plain language, with the rule of 45 and tips for beginners.
Killer sudoku rulesPrefer paper?
Print free killer sudokus on A4: 1, 2, or 4 per sheet, large print available, with solutions at the back.
Print killer sudokuFrequently asked questions about killer sudoku
How is it different from regular sudoku?
All the normal rules apply, but cages are added: groups of cells with a sum label. On the higher levels there are few or no starting digits — you reason mainly with the sums.
Do I need to be good at arithmetic?
Adding up to 45 is enough. The skill is not fast arithmetic but clever combining: which digits could form this sum together? That is exactly what makes killer sudoku such good brain training.
Can a digit repeat within a cage?
No. Within one cage all digits are different — that, next to the sum, is precisely what a cage tells you. The error check points it out if it happens anyway.
Is killer sudoku harder than regular sudoku?
Different, mostly. Easy gives you starting digits and is a gentle introduction; on Hard and Expert the grid starts (almost) empty and it is a proper challenge. Pick from four levels.
What does it cost?
Nothing. Killer sudoku is free, without an account and without hidden costs — like every puzzle on BreinPlezier.