Killer Sudoku: Rules, Tips, and How to Get Started
Killer Sudoku takes the familiar 9x9 grid and adds a twist: instead of starting with given numbers, you get cages with target sums. Every cage tells you what its digits must add up to, and no digit can repeat inside a cage.
How Killer Sudoku Works
The standard Sudoku rules still apply. Every row, column, and 3x3 box must contain the digits 1 through 9, each exactly once. Killer Sudoku adds three more rules:
- Cages: The grid is divided into groups of cells outlined by dotted lines. Each group is called a cage.
- Target sums: A small number in the corner of each cage tells you the total. The digits inside must add up to exactly that number.
- No repeats in cages: You cannot use the same digit twice within a single cage.
Most Killer Sudoku puzzles start with an empty grid. All your information comes from the cage sums and the standard row/column/box constraints.
Three Tips to Start Solving
1) Look for cages with only one possible combination
A 2-cell cage that sums to 3 can only be 1 and 2. A 2-cell cage summing to 17 must be 8 and 9. These locked combinations give you immediate progress.
2) Use the 45 rule
Every row, column, and 3x3 box sums to 45. If a cage is fully inside one row or box, you can find missing values by subtracting known sums from 45.
3) Cross-check cages with row and column constraints
Once a cage has only a few possible combinations, surrounding row/column/box limits usually remove at least one option and often force a value.
Want the full strategy toolkit? Our complete Killer Sudoku guide includes a full combinations table and deeper solving techniques.
Ready to Try One?
Killer Sudoku uses the same logical muscles as Hard and Expert standard Sudoku. If you want to warm up, start with our Hard difficulty printables first.
FAQ
What is the difference between killer sudoku and regular sudoku?
Regular Sudoku gives you some pre-filled digits and asks you to complete the grid using elimination. Killer Sudoku replaces those given digits with cages and target sums. You still cannot repeat a digit in any row, column, or box, but now you also cannot repeat a digit within a cage, and every cage must hit its sum.