Play more Killer Sudoku
Unlimited killer sudoku at four levels on the 9x9 grid, plus 6x6 and 4x4 boards to learn on. Each puzzle has one solution, and its level is the hardest technique it needs, from cage combinations to the rule of 45 across several houses.
This puzzle
Loading ยท the grid and its level
(a small spoiler)
Checked: exactly one solution, reachable by logic. The level is the hardest technique our solver needed, not the grid size.
Settings
Rule breaks (a repeated digit) always show in red. "Show mistakes" also marks cells that disagree with the solution.
The small boards
A 4x4 killer (boxes of 2x2, digits 1 to 4) is a five-minute lesson in cage sums; a 6x6 (boxes of 2x3, digits 1 to 6) adds the rule of 21, the small cousin of the rule of 45. Both are good warm-ups before the 9x9.
| Size | Level | Puzzles | Median steps | Need a tier-3 or harder technique |
|---|---|---|---|---|
| 4x4 | Easy | 50 | 19 | 0% |
| 6x6 | Easy | 50 | 54 | 0% |
| 6x6 | Medium | 50 | 57 | 0% |
| 9x9 | Easy | 50 | 145 | 0% |
| 9x9 | Medium | 50 | 159 | 0% |
| 9x9 | Hard | 50 | 174 | 100% |
| 9x9 | Expert | 50 | 183 | 100% |
Source: the Gridaday bank, 350 puzzles of Killer Sudoku graded by our solver; data as of 2026-10-17.
Easy to expert killer sudoku
- Killer sudoku, Easy: small cages and a few revealed digits; cage combinations and singles finish it.
- Killer sudoku, Medium: the rule of 45 on one row, column or box, which no Medium puzzle can be finished without.
- Killer sudoku, Hard: usually the rule of 45 on two or three neighbouring houses at once (90 or 135), to pin the cells that stick out.
- Killer sudoku, Expert: everything Hard needs, plus one short what-if check that the hint walks you through.
Killer sudoku online, hard or expert, is the 9x9 grid: pick Hard for hard killer sudoku online; expert killer sudoku is the same grid with that one extra step. When you play killer sudoku Expert online, the hint shows that what-if check one move at a time.
Challenge a friend
After you solve a puzzle, "Challenge a friend" copies a link to the same Killer Sudoku with your time. Your friend gets exactly your grid; nothing else is shared, and nothing goes through our servers.