Expert Irregular Sudoku

Jigsaw-shaped regions replace the 3×3 boxes. Rows, columns, and irregular regions must each hold 1–9. No download, no login.

Easy Medium Hard Expert

Expert Irregular Sudoku. The hardest jigsaw puzzles on the site — every placement requires multi-constraint reasoning across regions, rows, and columns. No guessing.

1
9
4
4
8
6
7
1
4
6
3
8
9
3
8
5
4
8
1
3
5
7
9
1
Mistakes
0/3
Score
-
Time
00:00
All Jigsaw Sudoku Puzzles →
Progress0%

What is Jigsaw Sudoku?

Difficulty
★★★☆☆
3/5
Constraint Type
Irregular Regions
Typical Givens
24–30
Avg. Solve (Expert)
60 min

Solving Techniques for Expert Level

Technique Description Level
Region Identification First Identify all 9 irregular regions by their colour coding before solving. Region membership determines the third constraint unit for each cell. Beginner
Region Counting Each region must contain 1–9. Counting completed rows and columns reveals how many of each digit can still fit in each region. Intermediate
Region–Row/Column Intersection If a digit within a region is confined to one row or column, eliminate it from the rest of that row or column. Intermediate
Irregular Naked Subsets Apply naked pairs and triples within each irregular region exactly as you would within standard 3×3 boxes. Advanced

Average Solve Time by Difficulty

Easy
7 min
Medium
16 min
Hard
32 min
Expert
60 min
Want a full walkthrough of rules, strategies, and solving steps? How to Play Jigsaw Sudoku →

Frequently Asked Questions — Expert Irregular Sudoku

Is expert Irregular Sudoku solvable without guessing?
Yes — every expert puzzle on Sudoku.by has a unique solution reachable by pure logic. No guessing or trial-and-error is required. Expert puzzles demand chaining multiple advanced techniques together, but every step follows from provable reasoning.
What advanced techniques are needed for expert Irregular Sudoku?
Expert puzzles typically require X-Wings or Swordfish patterns applied across regions, forcing chains, and multi-region elimination chains. You may also need to exploit the specific geometry of the regions — for instance, two regions that together cover exactly one full row allow a powerful sum-based elimination.
How do forcing chains work in Irregular Sudoku?
A forcing chain starts with an assumption — say, cell A holds digit X. You follow the logical consequences through regions, rows, and columns until you reach either a contradiction (proving X is wrong) or a confirmed placement elsewhere. Irregular regions often create shorter chains than standard Sudoku because of how regions cross multiple rows and columns.
How many givens does an expert Irregular Sudoku have?
Expert puzzles typically have 20–26 givens, spread across the board in a way that minimises obvious singles. The region shapes are chosen to make early progress very slow, requiring advanced multi-step logic before any cluster of placements unlocks.
How long does an expert Irregular Sudoku take to solve?
Expert Jigsaw Sudoku takes most players 60–90 minutes. If you've been stuck for more than 20 minutes, revisit every region and look for a hidden single or pointing pair you may have missed — these are almost always the key that unlocks expert grids.

More questions? See the full Irregular Sudoku guide.