What makes Expert so tough?
Expert puzzles have no starter numbers and the cages can have up to five cells. The sums are bigger, the combos are trickier, and there’s less info to work with.
But every Expert puzzle on this site has exactly one answer, and you can solve it without guessing. Use logic, take breaks, trust your notes!
If Expert feels overwhelming, that’s normal — even adults find it tough. Spend a few weeks at Hard Killer Sudoku first; the techniques are exactly the same, just with smaller cages and (sometimes) a few starter numbers.
Combos worth memorising
- 🔢 2-cell sums: 3 (1+2), 4 (1+3), 16 (7+9), 17 (8+9)
- 🔢 3-cell sums: 6 (1+2+3), 7 (1+2+4), 23 (6+8+9), 24 (7+8+9)
- 🔢 4-cell sums: 10 (1+2+3+4), 30 (6+7+8+9)
- 🔢 Anywhere a sum has only one combo, you’ve narrowed those cells to a tiny set of digits
Expert solving routine
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Auto Notes first
Tap it the moment the puzzle loads. You’ll see every candidate digit at a glance.
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Lock single-combo cages
Find any cage where only one combo works. Pencil all those digits into all those cells.
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45 rule everywhere
In every row, column and box, the cage totals add up to 45. Use that to find one mystery cell at a time.
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Hunt naked pairs and triples
After Auto Notes, look for two cells in a row with the exact same two candidates — those numbers are locked there.
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Place, repeat, win
Each placement narrows things down for everyone else. Keep going until the board is full!
When you’ve mastered Expert
Once Expert Killer puzzles feel comfortable, try our toughest Expert 9×9 sudoku. It’s a different kind of challenge — pure logic, no adding — but the same long-thinking patience pays off.
Or play a few rounds at lower difficulties just for the fun of it. Some of the most satisfying sessions are speeding through Hard Killer Sudoku puzzles in five or ten minutes.
Frequently asked questions
How long does an Expert puzzle take?
Most kids who can solve Expert finish in 25 to 45 minutes. Some take more than an hour — that’s normal! There’s no time limit.
Can I really solve Expert without guessing?
Yes! Every puzzle on this site has exactly one solution and was checked by computer to be solvable with logic alone. If your guess turns out wrong, just tap Undo.
What if I’m really stuck?
Tap the Hint button — it fills one correct cell so you can keep going. Hints count in your stats, but they’re there to help.
Is there anything harder than Expert Killer?
On this site, Expert Killer is the toughest cage puzzle. Some sites have an "Inhuman" or "Diabolical" level — but those are designed for adult sudoku-club regulars, not kids.
Try other sudoku games
Different rules, same friendly board. Pick a sibling puzzle to play next.