Fill every row, column and box
Just like classic sudoku: each row, column and 3×3 box holds the digits 1 to 9 exactly once.
Killer Sudoku
Free online puzzles. Every one is checked for a single solution you can reach by logic alone — no guessing.
Medium · #k9-000197
0:00
Cage 22 · 3 cellsAll combinations
589679
How to play Killer Sudoku
Make each cage add up
Dashed outlines are cages. The digits inside a cage must add up to the small number in its corner.
No repeats inside a cage
A digit can appear only once in each cage. There are no starting numbers — the sums are your clues.
Get better at Killer
All strategies → Beginner Cage combinations Some sums can only be made one way. Spot them first. Beginner The 45 rule Every row, column and box adds up to 45. Use it to find lone cells. Intermediate Innies and outies Cells poking in or out of a box give away their values. Intermediate Killer pairs Two cells that share the same two digits clean the rest of the house.
Questions
Is Killer Sudoku harder than regular sudoku?
It starts empty, so it feels harder at first. Once you know the common cage combinations, easy puzzles go quickly.
Does every puzzle have one solution?
Yes. Each puzzle is verified to have exactly one solution, reachable with logic — you never need to guess.
Can I print the puzzles?
Yes. Every difficulty has free printable sheets with answer pages.