How to play 4 × 4 Killer Sudoku
Fill the grid using the numbers 1–4. The Sudoku rules and the cage sums must all fit at the same time.
Play a mini puzzleThree rules
- Every row, column and bold 2 × 2 box contains 1, 2, 3 and 4 exactly once.
- The numbers inside each dashed cage add up to the small total in its corner.
- Numbers never repeat inside a cage, even if its cells lie in different rows, columns or boxes.
Start with a small cage
A two-cell cage totaling 3 contains 1 and 2. Its sum does not tell you their order. If the left cell’s column already has a 2, the left cell must be 1.
A one-cell cage is a direct clue: enter its printed total. In a two-cell cage totaling 4, the pair is 1 and 3. Two 2s would reach the total but break the no-repeat rule.
Useful pairs
| Two-cell total | Possible numbers |
|---|---|
| 3 | 1 + 2 |
| 4 | 1 + 3 |
| 5 | 1 + 4 or 2 + 3 |
| 6 | 2 + 4 |
| 7 | 3 + 4 |
Each row adds up to 10
Because 1 + 2 + 3 + 4 = 10, every complete row, column and box totals 10. If three cells in a row total 6, its remaining cell must be 4. Cage totals can help you find these smaller missing pieces.
Controls and corrections
Tap a cell and choose 1–4. The cage readout shows the sum of its entered digits beside its target. Use arrow keys to move, 1–4 to enter, and Backspace, Delete or 0 to clear. Home and End move to the row edges.
A marked ! means an entered digit conflicts with a row, column, box or cage rule. You can keep editing it or use Undo. A board with no marked conflict may still contain a wrong guess. Hint corrects a wrong entry first; otherwise it fills a blank. Undo also reverses a hint.
A smaller version of Killer Sudoku
Classic Killer Sudoku usually uses 9 × 9 grids, numbers 1–9 and 3 × 3 boxes. Cagefern’s mini version uses 4 × 4 grids, numbers 1–4 and 2 × 2 boxes. The same cage-sum and no-repeat rules apply.
All 24 puzzles are original and have one complete solution. Daily repeats every 24 days at 00:00 UTC. Practice cycles through the same 24 puzzles. Reopening after midnight keeps your previous daily until you choose Play today. Daily and practice are saved separately in this browser.
Restart and replacing an unfinished puzzle ask for confirmation. A numbered storage error explains how to retry or recover; an unreadable old record stays protected until you explicitly reset it.
Full-size rule references: Puzzler’s Killer Sudoku guide and Killer Sudoku Online’s rules.