Killer Sudoku starts with the familiar 9×9 grid. Each row, column and bold 3×3 box needs every digit from 1 to 9 exactly once. The difference is in the dashed cages: each group of cells has a target sum, shown in its top-left cell.
Use distinct digits in each cage. A two-cell cage totalling 3 must contain 1 and 2; a three-cell cage totalling 24 must contain 7, 8 and 9. The sum tells you which digits are possible, but their positions still need to satisfy Sudoku rules.
Select a square, then tap a number or use your keyboard. Press N for pencil notes, Backspace to erase, or use Undo to step back. Cage totals update as you fill, and overfilled cages are flagged without revealing the answer.
A thoughtful route to the answer
Start with the tight combinations
Small or unusually high cage totals often have only one digit combination. Pencil those candidates in, then use the surrounding rows and boxes to decide their order.
Remember 45
The digits 1–9 add up to 45. If complete cages cover all but one cell of a row, column or box, subtract their sums from 45 to find the missing value.
Use the cage as another unit
Removing a digit from a row is only half the story. A cage cannot repeat a digit, even when it stretches across a box boundary. Keep both sets of restrictions in mind.
Each row below has exactly one unordered combination of distinct digits. The cells may take those digits in any order permitted by the grid. These are useful anchors, not a complete list of every possible cage total.
Cells in cage
Target sum
Only possible digit combination
2 cells
3
1 + 2
2 cells
4
1 + 3
2 cells
16
7 + 9
2 cells
17
8 + 9
3 cells
6
1 + 2 + 3
3 cells
7
1 + 2 + 4
3 cells
23
6 + 8 + 9
3 cells
24
7 + 8 + 9
4 cells
10
1 + 2 + 3 + 4
4 cells
11
1 + 2 + 3 + 5
4 cells
29
5 + 7 + 8 + 9
4 cells
30
6 + 7 + 8 + 9
Your daily puzzle, your own pace
Choose Easy to learn with eight starting digits, or Medium and Hard for cage-only boards. Single-cell cages, when present, directly reveal a digit through their sum. The daily board is seeded by its UTC date and difficulty, so everyone choosing the same settings gets the same challenge. Unlimited mode creates a fresh board whenever you are ready; the archive lets you revisit the last 30 days.
Progress and streaks are saved on this device. One completed daily board per date counts towards the streak; switching difficulty does not award extra days. Hints are counted in your shareable result. Looking for the classic game? Play Daily Sudoku.
Killer Sudoku FAQ
What is Killer Sudoku?
Killer Sudoku combines classic Sudoku with sum cages. Fill each row, column and 3×3 box with 1–9. Digits inside each dashed cage add up to its small printed total and may not repeat within that cage.
Can a digit repeat inside a cage?
No, even when the two cells are in different rows, columns or boxes. Cage combinations always use distinct digits.
Can I play Killer Sudoku without starting numbers?
Yes. Medium and Hard have no pre-filled digits. Some cages can be a single cell, whose sum fixes that digit. Easy adds eight starting digits to make the rules easier to learn.
Does every generated puzzle have exactly one solution?
Yes. A solver checks cage sum combinations, Sudoku candidates and backtracking before accepting the cage layout. Unproven or multiple-solution merges are rejected.
When does the daily Killer Sudoku change?
At midnight UTC. Everyone choosing the same date and difficulty gets the same board. The last 30 daily dates are available in the archive.
How do pencil notes work?
Select Notes or press N, then use 1–9 to toggle small candidate digits. Turn notes off to enter a full-size digit. Undo restores the previous move.
Is progress saved and is there an API cost?
Progress and your daily streak are stored in this browser only. Puzzle generation runs locally with no paid API, account, or upload. Clearing site data removes saved progress.
Are these difficulty ratings official?
No. Easy, Medium and Hard are relative generator settings based on givens, cage size and bounded solver search, not an externally calibrated rating.