SudokuRows, columns, boxes
As in classic Sudoku, every row, column, and 3×3 box contains the digits 1 to 9 exactly once.
SUMS, CAGES, AND LOGIC
Killer Sudoku
Classic Sudoku plus cages that add up to a sum. Few or no starting digits, just logic and a little arithmetic.
KILLER SUDOKU
Add it all up.
A moment to pause.
Your puzzle will be right here.
Puzzle progress0%
Loading puzzle…
1–9 to fill · Shift+1–9 for notes · Arrows to move · Delete to erase
◇ No account needed✓ Always free to play◎ Made for your focus
KILLER SUDOKU RULES
Sudoku, plus a little arithmetic
Classic rules, with cages and sums.
Few or no starting digits.
Add up to the sum
The dashed outlines are cages. The digits inside a cage must add up to the small number in its corner.
Unique inside a cage
A digit can never appear twice in the same cage, even when the cage crosses two boxes.
KILLER TECHNIQUES
Start playing ↗How to solve Killer Sudoku
Start with unique combinations
Some cages have only one possible set of digits. Two cells summing to 3 must be 1 and 2; two cells summing to 17 must be 8 and 9. Select a cage and the game lists every combination that fits.
Use the rule of 45
Every row, column, and box adds up to 45. If cages cover a box except for one cell, subtract their sums from 45 to find that cell.
Combine cages and lines
When a cage sits entirely inside one row or box, its digits are locked there. Treat its combination like a naked pair or triple and eliminate those digits elsewhere.
Take notes
Write the possible digits of each cage in notes, then apply classic Sudoku techniques. Our strategy guides cover singles, pairs, and more.
Every Killer Sudoku here is checked to have exactly one solution. Hard puzzles start with no digits at all: only the cages guide you. Prefer paper? Choose Killer on the printable page.
KEEP PLAYING
More free Sudoku puzzles
Daily SudokuOne shared puzzle a day.Easy Sudoku43 clues, perfect to start.Medium Sudoku36 clues, room to think.Hard Sudoku30 clues, notes recommended.Expert SudokuAbout 25 clues, beyond singles.6×6 SudokuDigits 1 to 6, great for kids.Sudoku SolverSolve any puzzle, step by step.Printable SudokuPrint or save as PDF.Sudoku StrategiesLearn every solving technique.
GOOD TO KNOWA little clarity
A little clarity
before you play.
The details, without the distractions.
What is Killer Sudoku?
A Sudoku variant that adds cages: groups of cells outlined with dashes, each with a sum. The digits in a cage must add up to that sum and cannot repeat. The classic row, column, and box rules still apply.
Is Killer Sudoku harder than regular Sudoku?
It usually feels harder at first because puzzles start with few or no digits. Once you know the common cage combinations and the rule of 45, it becomes very satisfying.
What is the rule of 45?
The digits 1 to 9 add up to 45, so every row, column, and box totals 45. Comparing that with the cage sums lets you deduce single cells or small groups.
Do the puzzles have a unique solution?
Yes. Every Killer Sudoku on Sudoku Prime is checked by a solver to have exactly one solution.
How are the difficulty levels different?
Easy uses small cages and a few starting digits. Medium uses cages of up to four cells and very few starting digits. Hard has no starting digits at all.