What "Expert" really means
An Expert sudoku has fewer than 25 starting numbers — over two-thirds of the grid is empty when you start. The puzzle still has exactly one solution and you can still find it without guessing, but you’ll need to be patient, careful and willing to combine several techniques in the same move.
If you’re comfortable with Hard sudoku — finishing most of them with three or fewer hints — you’re ready for Expert. If you’re not quite there yet, give it a few more weeks. Expert is harder than Hard in a meaningful way, and there’s no shame in mastering Hard first.
Most kids who tackle Expert spend 30–60 minutes on a single puzzle. Some split it across several sessions — your progress is saved automatically. Treat each puzzle like a small project rather than a quick game.
A solving routine that really works
-
Tap Auto Notes first
Don’t even try to solve Expert without your candidates filled in. Trust us. Even sudoku world champions write candidates on paper before they start an Expert puzzle.
-
Look for "lone candidates"
Any square with only ONE possible number? Fill it in. These are gold dust at Expert level — they’re rare but they always work.
-
Look for "hidden singles"
A row, column or box where a particular number is only possible in one square (even if that square has lots of other candidates)? Fill that in too. Hidden singles are far more common than lone candidates at Expert.
-
Use naked pairs and pointing pairs
Steal the techniques from the Hard guide — they really shine on Expert. A single naked pair often unlocks a chain of follow-up moves.
-
Take a Hint when truly stuck
Five minutes without a new answer? Tap Hint. One hint usually opens up several more answers because it completes a row or box.
-
Run Check before you celebrate
Before you fill in the last few squares, tap Check. If anything is wrong, you’d rather find out now than after typing in a wrong final answer.
Advanced techniques worth knowing
Some Expert puzzles need techniques that go beyond hidden singles and naked pairs. They have funny names — "X-wing", "swordfish", "XY-wing" — and they can sound scary, but each one is just a pattern you learn to spot.
You don’t need them all to enjoy Expert. Most Expert puzzles on this site can be solved with hidden singles, naked pairs, naked triples and pointing pairs. The really exotic techniques are mostly for sudoku competitions.
If you want to go deeper, try this: pick one new technique and look for it in three puzzles in a row. Even if you don’t spot it, you’ll start to recognise the shape. Then in the fourth puzzle, it’ll suddenly jump out at you.
Take your time
A typical Expert puzzle takes 30 minutes or more. Some kids enjoy splitting one puzzle across several short sessions — your progress is saved automatically, so you can come back to the exact same board hours or days later.
There are no points and no pressure here. Just the puzzle and your brain. The timer is just a counter — not a deadline. Some of the best sudoku players in the world deliberately go slowly so they make fewer mistakes.
A nice habit: start an Expert puzzle in the morning, do a few moves at breakfast, leave it open in another tab, and come back over the day. By dinner you’ll often have it solved — with no single sitting feeling like a slog.
When you’ve mastered Expert
Once Expert puzzles feel comfortable — you’re finishing them with two or three hints, in under 30 minutes — try our other variants. Killer Sudoku adds a little maths in the form of cage sums, and is genuinely different from classic sudoku. The same logical thinking applies, but you’re also adding small numbers as you go.
Or play a few rounds at lower difficulties just for fun. There’s no rule that says you have to play at the toughest level once you’re good at it. Hard sudoku puzzles in 5 minutes can be very satisfying.
Frequently asked questions
Can I really solve Expert without guessing?
Yes. Every puzzle on this site has exactly one solution and is designed to be solved with logic alone. If something doesn’t work, you’ve made a mistake somewhere — tap Check to find it.
How many hints is "too many"?
There’s no rule. Hints are a learning tool. If you finish an Expert puzzle with 5 hints and you understand every step, that’s a win. Next time you’ll likely need fewer.
My kid is stuck on the same puzzle for an hour. Is something wrong?
Probably not — Expert puzzles are genuinely hard. Tap Check to make sure no early answer was wrong. If everything looks clean, take one Hint and keep going.
Is there anything harder than Expert?
On this site, Expert is the toughest classic level. If you want a different kind of challenge, try Killer Sudoku at Expert difficulty — the cage sums add a whole new layer of logic.
What’s the difference between a "lone candidate" and a "hidden single"?
They’re close but not the same. A "lone candidate" means a square with only one possible number. A "hidden single" means a row/column/box where a specific number can only fit in one square (even if that square has other candidates too).
Try a different size
New to sudoku? Start with a smaller grid — you’ll learn the rules in a few minutes.