Free Killer Sudoku, Play Online or Print
22 killer sudoku puzzles you can solve in the browser, or print as a clean PDF with the solution. The grid starts empty, cage sums are your only clues, and every puzzle has exactly one solution. No signup, no watermark.
New to killer? Read how it works → · Classic sudoku →
Very Easy Killer
6Small cages and gentle sums. A good first killer if you already know normal sudoku.
Easy Killer
6Mostly two- and three-cell cages, so the arithmetic stays light while you learn cage logic.
Medium Killer
6Bigger cages and fewer easy givens-by-sum. You will lean on the 45-rule and cage combinations.
Hard Killer
4Large cages, sparse forced cells. Expect long chains of elimination before the grid opens up.
How killer sudoku works
A killer sudoku uses the same 9×9 grid as normal sudoku, and the same rule: every row, every column, and every 3×3 box must contain the digits 1 to 9 with no repeats.
The difference is that no numbers are given at the start. Instead the grid is divided into cages, marked by dashed outlines. The small number in the corner of a cage is the sum that the digits in that cage must add up to, and no digit may repeat inside a cage.
Three tips to get started
Hunt for extreme cage sums. A two-cell cage that sums to 3 can only be 1 and 2. One that sums to 17 can only be 8 and 9. Small cages with very high or very low sums pin down digits immediately.
Use the 45 rule. Each row, column and box totals 45. Add up the cages that sit fully inside a region, and the cells left over must make up the rest. This often reveals a single cell's value.
Pencil in combinations. For each cage, note which digit sets are possible for its sum, then cross them off as neighbouring cells and lines rule them out.
Frequently asked questions
What are the rules of killer sudoku?
The killer sudoku rules start from normal sudoku: fill each row, column and 3x3 box with 1 to 9, no repeats. Two things are added. The grid starts empty, and cells are grouped into dashed "cages" whose small corner number is the sum its digits must add up to, with no digit repeated inside a cage.
How do you solve a killer sudoku?
Start with small cages that have extreme sums, since they have only one or two digit combinations. A two-cell cage summing to 3 must be 1 and 2; a two-cell cage summing to 17 must be 8 and 9. Those give you your first footholds, then the 45 rule opens up the rest.
What is the 45 rule?
Every row, column and box contains 1 to 9, which always sums to 45. If cages cover a region and you know their total, the leftover cells must make up the difference from 45. It is the most useful killer technique.
Do I need to be good at maths?
Only simple addition. The puzzle is still logic, not arithmetic, the sums just give you extra clues about which digits can go where.