Killer Sudoku Printable Generator
9×9 with cage sums. Color or black & white.
Killer sudoku rules
Killer sudoku follows all standard sudoku rules — each row, column, and 3×3 box must contain the digits 1 through 9 exactly once — and adds one more constraint: the grid is divided into dashed "cages" of two to five cells, and the digits inside each cage must add up to the small number printed in its top-left corner. No digit may repeat within a single cage. There are no starting numbers, so every clue is a sum; the math acts as the puzzle's skeleton while standard sudoku logic does the rest. Start by finding cages whose sum forces the digits (a two-cell cage summing to 3 must be 1+2; a two-cell cage summing to 17 must be 8+9), then propagate constraints into surrounding rows and columns. Print one to start, two when you're ready for a longer sit-down.
How to solve killer sudoku — a beginner's guide
Killer sudoku looks intimidating because the grid starts empty, but the dashed outlines and the little numbers in the corners do the work that starting clues do in a regular puzzle. Each dashed outline marks a cage — a small group of two to five cells that belong together. The number in the top-left corner of the cage is the cage sum: the digits inside that cage must add up to exactly that total. The classic sudoku rule still applies, so every row, column, and 3×3 box must contain the digits 1 through 9 exactly once, and there is an extra constraint on top: a digit cannot repeat inside a single cage either.
The fastest way into a killer is to find cages whose sum forces the digits. A two-cell cage with the sum 3 has only one possible content: the digits 1 and 2, in some order. A two-cell cage with the sum 17 can only be 8 and 9. A three-cell cage summing to 6 must be 1, 2, and 3. Mark these candidate pairs lightly in pencil and then look at where those cages sit. If your "1 or 2" cage shares a row with another cage that already includes a definite 1, the 1 in your cage moves to the other cell and the 2 falls into place.
From there, combine cage logic with standard sudoku elimination. Once a cell is fixed, sweep its row, column, and box like any normal sudoku, then revisit neighbouring cages — the new digit usually narrows another cage's options. Work in short loops: solve a forced cage, propagate the consequences, then look for the next forced cage. A killer rarely rewards staring at one square; it rewards walking the grid in circles, picking up one or two cells per lap.
A concrete example: imagine a two-cell cage in the top row summing to 4, sitting directly above a single-cell cage of 1 in the second row. The top cage must be 1 and 3. The 1 in the second row already lives in that column, so the 1 in your top cage cannot sit in that column either — it must be in the other cell, which fixes the 3. You have just solved two cells using nothing but a cage sum and a single given digit.
Killer sudoku vs regular sudoku — what's different?
| Feature | Regular sudoku | Killer sudoku |
|---|---|---|
| Given numbers shown | Yes | No |
| Uses cage sums | No | Yes |
| Requires arithmetic | No | Yes (simple addition) |
| Suitable for beginners | Yes | Intermediate+ |
| Solving techniques | Elimination only | Elimination + sum logic |
Killer sudoku tips
Before you write a single digit, list the possible combinations for every cage in the margin. A two-cell cage summing to 5 is either 1+4 or 2+3, and writing that down once saves you recomputing it five times during the solve.
Cages that span an entire row or column are gold. If a row contains a single cage of all nine cells, that cage must sum to 45 and contain every digit — and any cage that crosses into that row inherits a tight constraint.
Small cages do the heavy lifting. A two-cell cage usually has only one or two possible combinations, so solve every small cage on the board before touching the larger ones. The big cages tend to resolve themselves once the small ones are pinned down.
Use pencil marks for cage candidates, not just cell candidates. Writing a tiny "1/4 or 2/3" next to a cage tells you instantly what the cage can hold without recomputing the sum every time you look at it.
When you stall, reach for the 45 rule. Any complete row, column, or 3×3 box must total 45. Add up the cage sums fully inside that row or box, and the remainder tells you what any partial cage poking into the area must sum to. This trick cracks more "impossible" killers than any other technique.
🖨️ How to Print Your Puzzle Correctly▼
Cage Combinations Cheat Sheet
Every possible number combination for every cage size and sum — the reference sheet serious killer sudoku players keep close. Print it, laminate it, use it daily.
Create Your Own Killer Sudoku
Draw your own cages and set your own sums. A creative challenge for experienced players and a great classroom activity.
Frequently asked questions — killer sudoku
Is killer sudoku harder than regular sudoku?+
Yes, in general. A killer at any given difficulty rating takes longer than a regular sudoku at the same rating because you have to track cage constraints alongside the standard row, column, and box rules. An easy killer is roughly equivalent to a medium regular sudoku.
Do I need to be good at maths to solve killer sudoku?+
Not really. The only arithmetic involved is adding two to five small numbers, which is well within reach for anyone comfortable with basic addition. Killer rewards logical reasoning far more than calculation speed.
What does the number in the corner of a cage mean?+
It is the cage sum — the total that the digits inside that cage must add up to. No digit may repeat within the cage, so the combinations are usually quite limited and form the puzzle's main starting clues.
Can children solve killer sudoku?+
Strong puzzle-solvers around age ten or eleven can manage an easy killer once they are confident with regular 9×9 sudoku. Below that, stick with 4×4 and 6×6 regular puzzles — killer's extra layer of constraints tends to overwhelm younger solvers.