Easy Killer Sudoku
Mistakes
0/3
Score
-
Time
00:00
14
9
17
9
7
21
4
9
8
18
24
21
6
4
11
18
4
12
13
19
21
15
13
16
6
12
28
11
1
19
6
9
How to play Killer Sudoku
The board starts with pre-filled digits as clues. Your clues are the cage sums (small numbers in cell corners). Fill each cage so the digits sum to that total, with no repeats within any cage. All standard Sudoku rules still apply (1–9 in every row, column and 3×3 box).
Killer Sudoku - Complete Guide
Difficulty Overview
| Level | Given digits | Cages | Avg. solve time |
|---|---|---|---|
| Easy | ~26 | ~28–32 | 5–10 min |
| Medium | ~18 | ~30–36 | 10–20 min |
| Hard | ~8 | ~34–40 | 20–40 min |
| Expert | 0 | ~36–45 | 40–90 min |
Cage Sum Limits
| Cage size | Min sum | Max sum | Forced? |
|---|---|---|---|
| 1 cell | 1 | 9 | Yes (unique) |
| 2 cells | 3 | 17 | At extremes |
| 3 cells | 6 | 24 | At extremes |
| 4 cells | 10 | 30 | At extremes |
| 5 cells | 15 | 35 | At extremes |
| 9 cells | Always 45 | Yes | |
Forced cage combinations you must memorise
2-Cell cages - Forced sets
| Sum | Only possible set |
|---|---|
| 3 | {1, 2} |
| 4 | {1, 3} |
| 16 | {7, 9} |
| 17 | {8, 9} |
3-Cell cages - Forced sets
| Sum | Only possible set |
|---|---|
| 6 | {1, 2, 3} |
| 7 | {1, 2, 4} |
| 23 | {6, 8, 9} |
| 24 | {7, 8, 9} |
Key solving techniques
45 Rule
Every row, column, and 3×3 box sums to 45. If all cages in a row are known except one cell, the missing value = 45 − (sum of all other cage totals in that row). This is the single most powerful Killer technique.
Innies and Outies
When a cage partially straddles a row/column/box boundary, the cells inside the boundary are "innies" and those outside are "outies." Their sum difference reveals exact values using the 45 rule, often resolving cells without any candidates.
Cage Elimination
No digit may repeat within a cage. List all combinations that produce the cage sum, then cross-eliminate those that conflict with placed digits in the same row, column, or box. Often narrows a cage to a single combination early in the solve.
Naked Subsets in Cages
When two cells in a cage can only hold two specific digits (a naked pair), those digits are locked into that cage and can be eliminated from the rest of their shared row, column, or box - Exactly like standard Sudoku naked pairs.
Difficulty comparison - Constraint density
Higher constraint density = fewer given digits but more cage interactions per cell on average.
Easy
32%
Medium
52%
Hard
72%
Expert
100%
Frequently asked questions
Can a digit repeat inside a cage? +
No. Each digit must appear at most once within any cage, in addition to not repeating in its row, column, or 3×3 box. This is the core extra constraint of Killer Sudoku.
Do I need to do arithmetic to solve it? +
Basic addition is required. You need to figure out which digit combinations produce each cage sum. No multiplication or complex maths - Just 1–9 addition. Memorising the forced 2- and 3-cell combinations above covers the most common cases.
What does sharing a puzzle do? +
The Share button copies a URL containing the puzzle ID. Anyone who opens that link will see the exact same cage layout you are solving - Useful for competing with friends or comparing solve times on the same puzzle.
How is the score calculated? +
Score = max(0, 10 000 − time×10 − mistakes×200 − hints×500). Finishing faster with no mistakes and no hints gives the highest possible score of 10 000.
Explore More Sudoku Variants
Killer Sudoku - Complete Guide
Forced cage combinations you must memorise
Key solving techniques
45 Rule
Every row, column, and 3x3 box sums to 45. If all cages in a row are known except one cell, the missing value = 45 - (sum of all other cage totals in that row). This is the single most powerful Killer technique.
Easy tip -
Start every puzzle by scanning for forced cages (sums of 3, 4, 16 or 17 in 2 cells). These give you free digits immediately. Then apply the 45 rule to any row or column where only one cage cell is unknown.