Killer Sudoku
Fill the grid so every row, column and box holds the digits 1 to 9 once, and the digits in each dashed cage add up to the number in its corner without repeating. There are no given digits, and every puzzle has one solution you can reach by logic alone.
How to play Killer Sudoku
How to play
Tap a cell, then tap a number on the pad (or type 1 to 9). As in Sudoku, each digit appears once in every row, column and 3×3 box. The digits in a dashed cage add up to the total in its corner and never repeat inside the cage. Turn on Notes (or press N) to pencil in candidates.
Cage combinations
Some totals can be made only one way: a 2-cell cage of 3 is 1 and 2, a 2-cell cage of 17 is 8 and 9, and a 3-cell cage of 6 is 1, 2 and 3. Select a cell to see the ways its cage can still be made with the digits you have placed. A digit that a cage must use can’t appear anywhere else in a row, column or box the cage lies in.
The 45 rule
The digits 1 to 9 add up to 45, so every row, column and box does too. If the cages wholly inside a box add up to 38 and one cell of the box is left over, that cell must be 7. If the cages that cover a row add up to 52, the one cell sticking out of the row must be 7. It works the same for two or three neighbouring rows or columns, which add up to 90 or 135.
Levels and hints
Levels are set by the hardest step a logical solver needs. Gentle needs only cage combinations, singles and digits a cage must use. Moderate adds the 45 rule for a single cell, pairs, pointing, and a cage that holds a digit’s only places in a row, column or box. Tough adds the 45 rule over two or three cells, two cages in one row, column or box that can’t share a digit, triples, X-wings and XY-wings. Hint applies one such step and explains it in a sentence.
Questions
What are the rules of Killer Sudoku?
Fill the 9×9 grid so each row, column and 3×3 box contains the digits 1 to 9 once. The grid is also split into cages: the digits in each cage add up to the small number in its corner, and a digit can’t repeat inside a cage.
How is Killer Sudoku different from Sudoku?
A normal Sudoku starts with given digits. These Killer Sudoku puzzles start with none: you work from the cage totals instead, using a little arithmetic alongside the usual Sudoku logic.
What is the 45 rule in Killer Sudoku?
Because 1 to 9 add up to 45, every row, column and box adds up to 45. Compare that with the totals of the cages inside or around it and you can often work out one cell, or the sum of two or three cells. Hints here use the rule and show the sums.
Does every Killer Sudoku here have exactly one solution?
Yes. Every puzzle was checked by a solution counter that found exactly one solution, and finished by a logical solver at its difficulty level, so you never need to guess.
Is there a daily Killer Sudoku?
Yes. The daily puzzle is a Moderate Killer Sudoku that is the same for everyone and changes at midnight UTC.