Expert Sudoku Puzzles

Expert Sudoku is where solving becomes an art form. With 22–26 starting clues, these puzzles demand techniques that look beyond individual rows, columns, and boxes to find patterns spanning the entire grid. If you’ve conquered hard Sudoku and want to push further, expert is the level that separates committed solvers from casual players.

At expert, your foundational techniques — singles, pairs, triples, and pointing pairs — still handle the early and middle stages of solving. But every expert puzzle has at least one point where those techniques stall, and you need a grid-wide perspective to continue.

How Expert Differs from Hard and Evil

Coming from Hard

Hard Sudoku keeps the action mostly local: pointing pairs, box-line reduction, and triples all operate within a single unit or between adjacent units. Expert puzzles introduce a fundamentally different class of techniques — fish patterns and wings — that require scanning across multiple non-adjacent rows or columns simultaneously.

The key differences:

  • Fewer starting clues (22–26 vs. 26–30). This creates a denser candidate grid with more possibilities per cell, requiring sharper elimination before placements emerge.
  • Grid-spanning techniques are mandatory. At least one X-Wing, Swordfish, XY-Wing, or XYZ-Wing is typically needed per puzzle. These can’t be replaced by applying more pairs or triples.
  • Deeper candidate analysis. Expert puzzles require you to maintain accurate candidate lists throughout and notice relationships between cells that may be far apart on the grid.

Moving to Evil

Evil Sudoku is the final step up. While expert puzzles typically require one or two grid-spanning techniques to break through, evil puzzles require chains — multi-step logical sequences that trace candidate relationships across many cells before producing a single elimination. Evil puzzles also have even fewer starting clues (17–22), and the techniques themselves are harder to spot because the patterns are less visually obvious.

Think of it this way: expert techniques like X-Wing have recognizable visual patterns (a rectangle shape on the grid). Evil techniques like alternating inference chains require you to reason abstractly about “if this cell is 5, then that cell can’t be 3, which means…” — a fundamentally different cognitive skill.

Key Techniques for Expert Sudoku

X-Wing

An X-Wing occurs when a candidate number appears in exactly two cells in each of two different rows, and those cells align on the same two columns (forming a rectangle). The candidate can then be eliminated from all other cells in those two columns. The same logic applies with rows and columns swapped.

X-Wings are the gateway to grid-spanning logic. Once you learn to spot them, Swordfish and other fish patterns become natural extensions.

Practice spotting this pattern with our X-Wing practice puzzles.

Swordfish

Swordfish extends the X-Wing concept from two rows to three. When a candidate appears in two or three cells in each of three rows, and those cells are confined to the same three columns, the candidate can be eliminated from all other cells in those columns.

Swordfish patterns are harder to see because the cells don’t always form a clean rectangle. Some of the nine possible positions may be empty. Practice recognizing the partial pattern with our Swordfish practice puzzles.

XY-Wing

XY-Wing (also called Y-Wing) uses three cells with two candidates each to make an elimination. The pattern requires a “pivot” cell that shares one candidate with each of two “wing” cells. The key insight: the candidate shared between the two wings (but not the pivot) can be eliminated from any cell that sees both wings.

XY-Wings are powerful because they produce eliminations that no amount of row-column-box scanning can find. They’re also visually distinctive once you know what to look for. Study the technique in our XY-Wing guide and practice with XY-Wing puzzles.

XYZ-Wing

XYZ-Wing is the three-candidate extension of XY-Wing. The pivot cell has three candidates instead of two, and the shared candidate between the pivot and both wings can be eliminated from cells that see all three cells in the pattern.

XYZ-Wings are less common than XY-Wings but can crack puzzles where nothing else works. Learn the details in our XYZ-Wing guide and practice with XYZ-Wing puzzles.

Solving Workflow for Expert Puzzles

  1. Apply all foundational techniques. Singles, pairs, triples, and pointing pairs will carry you through the first 50–70% of the puzzle. Don’t try to jump to expert techniques early — exhaust the basics first.

  2. Build a complete candidate grid. Before looking for fish patterns or wings, ensure every candidate is accurately recorded. Missing candidates make these techniques impossible to spot.

  3. Scan for X-Wings. For each candidate number (1–9), check if it appears in exactly two cells in two different rows that share the same columns. This rectangular pattern is the most common expert technique.

  4. Check for XY-Wings. Look for bivalue cells (cells with exactly two candidates) that share candidates with other bivalue cells. The three-cell Y-shaped pattern often appears after some candidate elimination.

  5. Look for Swordfish if needed. If X-Wings and XY-Wings don’t break the puzzle, extend your search to three-row patterns for Swordfish.

  6. Iterate aggressively. Every expert-level elimination potentially unlocks several downstream placements. After each technique application, re-scan the entire grid from singles upward.

Common Expert-Level Mistakes

  • Hunting for expert techniques too early. Always exhaust singles, pairs, triples, and pointing pairs first. Many solvers waste time looking for X-Wings when a hidden triple would solve the same section.
  • Inaccurate candidate lists. Expert techniques require perfect candidates. One overlooked possibility and the pattern breaks. When stuck, audit your candidates before searching for complex patterns.
  • Only scanning rows. X-Wings and Swordfish work in both orientations — row-based and column-based. If you only check rows, you’ll miss half the patterns.
  • Forgetting about wings. Many solvers focus exclusively on fish patterns at this level. XY-Wings are just as common in expert puzzles and often easier to spot.

When to Move to Evil

You’re ready for evil Sudoku when:

  • You solve expert puzzles consistently, even if they take time.
  • X-Wings and XY-Wings feel natural and you spot them without systematic searching.
  • You’ve encountered puzzles where even expert techniques don’t seem sufficient.
  • You’re curious about chains, coloring, and multi-step deduction.

Frequently Asked Questions

What’s the difference between expert and hard Sudoku? Hard puzzles require local techniques like pointing pairs and triples. Expert puzzles additionally require grid-spanning techniques like X-Wing, Swordfish, and XY-Wing that analyze patterns across the entire grid.

How long does an expert Sudoku take? Most experienced solvers spend 20–45 minutes on expert puzzles. The time is heavily dependent on how quickly you spot the grid-spanning technique needed to break through. With practice, you’ll develop an eye for these patterns.

Do I need to know all fish patterns to solve expert puzzles? No. X-Wing and XY-Wing cover most expert puzzles. Swordfish and XYZ-Wing are useful but less frequently required. Learn X-Wing first, then add techniques as needed.

What if I can solve hard puzzles but expert feels impossible? The jump to expert is the steepest difficulty increase in Sudoku. Focus on learning one new technique at a time — start with X-Wing using our practice puzzles, then add XY-Wing. Don’t try to learn everything at once.

Explore our complete technique library and advanced strategy articles to master expert Sudoku. When you’re ready for the ultimate challenge, evil Sudoku awaits.