Expert Sudoku — Play Free Online
Free expert Sudoku — the hardest level here, at around 24 clues. These grids are built to remove the easy entry points, so expect long stretches with no placement at all, followed by a run of fifteen squares once you find the deduction that opens it.
- Clues to start
- about 24
- Par time
- 25 min
- Cost
- free, no sign-up
Very hard, but never unfair
Every puzzle on this page has exactly one solution, and that solution can always be reached by deduction. The generator stops removing clues the moment another removal would leave a grid with two possible answers, so a position that seems to demand a guess is a position where a deduction is being missed — not a puzzle that needs one.
What makes it expert is reach. The move you need may only appear after you have cleared away candidates that never get placed themselves. Five expert grids in six need an elimination technique somewhere — most often a naked pair, a pointing pair or a box/line reduction — and all of them are explained in the expert guide.
How to approach one
Fill in complete notes before hunting for anything clever — every technique at this level reads patterns out of the candidate marks, and a partial grid of notes hides exactly the pattern you are looking for. Then work systematically rather than by inspiration: one digit at a time, one unit at a time, in the same order each pass.
Give yourself permission to take two sittings. The par time is 25 minutes and the board saves itself on your own device, so stepping away costs nothing but the speed bonus.
Scoring at this level
Expert carries the largest completion bonus and the steepest speed bonus of the four levels, which is what makes it worth playing for a leaderboard place: a clean expert solve outscores a fast easy one by a wide margin. Mistakes cost 50 points each and hints 75, so a careful slow solve usually beats a quick messy one.
Scoring at the top level
An expert finish is worth 900 points — the largest bonus here — with 3 points per second under the 25-minute par. That rate is three times the easy one, so the leaderboard rewards a fast expert solve far above a fast easy one, which is the whole reason the bonus table is tiered.
A hint costs 75, which at this level is 25 seconds of speed bonus — cheap if it saves you ten minutes of staring. There is no virtue in refusing all three on principle; there is some in spending the first one only after you have worked through the techniques in order.
When you are genuinely stuck
Expert grids stall in a specific way: everything from the lower levels has been applied to exhaustion and the board has not moved. Insisting harder on those techniques will not help, because they have already given everything they have.
The move is to change what you are looking at. Stop examining units and start examining a digit across the whole grid: pick one, mark every square that could still take it, and look for a row where only two remain. Then look for a second row where the two remaining squares sit in the same two columns. That is an X-Wing — unfindable while you look at one box at a time. It is the rarest move these grids ask for: about one expert puzzle in fifty actually needs one, so try the pair techniques first.
Common questions
How many clues does an expert Sudoku have?
Around 24, which is close to the practical floor — a Sudoku with a unique solution needs at least 17 clues, and grids near that limit stop being enjoyable rather than becoming more interesting. The generator stops digging the moment another removal would leave two possible answers.
Is expert Sudoku solvable without guessing?
Yes. Every grid here has exactly one solution reachable by pure deduction, and the generator verifies that before the puzzle is ever shown. A position that feels like it demands a guess is a position where a deduction is being missed — most often an X-Wing, which spans two rows and two columns at once and is invisible while you examine units one at a time.
How long should an expert Sudoku take?
Twenty-five minutes is par for the speed bonus, and an hour is an ordinary time for this level. Expert grids are built to remove the easy entry points, so expect long stretches with no placement at all followed by a run of fifteen squares once the deduction that opens the grid turns up.
What technique do I need for expert Sudoku that I did not need before?
The X-Wing, in most grids. Find a digit with only two possible positions in each of two different rows, and check whether those positions fall in the same two columns. If they do, those two columns will take that digit in those rows whichever way round it goes, so it can be eliminated from every other square in both columns — often far from the four squares you started with.
Is there anything harder than expert here?
No, this is the hardest level on the site. If expert grids have stopped being a challenge, the interesting direction is speed rather than difficulty: the par time and the speed bonus turn a solved grid into a time to beat, and the daily puzzle gives everyone the identical grid so the comparison means something.
Other levels
- Easy Sudoku — about 42 clues.
- Medium Sudoku — about 34 clues.
- Hard Sudoku — about 28 clues.
- How to play Sudoku — the rules, plus a separate guide for each level.