X-Wing

What's an X-Wing?

X-Wing is the first advanced fish pattern most Sudoku players learn. It appears when the same digit shows up in exactly two cells in two rows (or two columns), and those cells align in the same two columns (or rows). Once you spot that 2×2 alignment, you can eliminate that digit from other cells in those columns or rows, often unlocking stalled puzzles without guessing.

This is a natural progression from naked pairs and builds on the foundation of naked singles and hidden singles. If you're still building your basics, consider reviewing pointing pairs as an intermediate bridge before tackling X-Wing.

Want to practice X-Wing on paper? Download our free printable Sudoku PDFs (A4 & US Letter) and try the technique on harder grids.

Why It's a Game-Changer

X-Wing is the first fish pattern in the family that includes Swordfish and Jellyfish. Once you spot one, you can remove misleading candidates and open up fresh possibilities — often triggering naked singles or hidden singles you couldn't see before.

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How to Spot and Apply an X-Wing (Step by Step)

1. Pick one digit and scan only that digit. Example: choose digit 6 and ignore all other candidates for this pass.
2. Find a row with exactly two candidates for that digit. Example: Row 4 has 6 only at c2 and c7.
3. Find a second row with the same two candidate columns. Example: Row 8 also has 6 only at c2 and c7.
4. Confirm the rectangle pattern. Example: r4c2, r4c7, r8c2, r8c7 form the X-Wing corners.
5. Eliminate that digit from other cells in those columns. Example: remove 6 from any other unsolved cells in column 2 and column 7.
6. Re-scan for follow-up singles. Example: after elimination, r6c7 may drop to one candidate and become a naked single.

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Visual Walkthrough

Imagine rows 4 and 8 both have exactly two "6" candidates - and they're both in columns 2 and 7. That forms a neat rectangle. Whether 6 is in (r4,c2) and (r8,c7) or in (r4,c7) and (r8,c2), you know both columns 2 and 7 must contain the six. So you can remove 6 as a candidate from any other cell in columns 2 and 7. That clean‑up often sparks progress.

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Common Pitfalls & Mix-ups

• Thinking any rectangle counts - not all 2‑by‑2 rectangles qualify. You need exactly two candidates in each row/column, and they must align.
• Ignoring symmetry - it works in both directions: rows→eliminate in columns and columns→eliminate in rows.
• Missing the logic - you're using disjunction: either diagonal placement A or B must happen, so candidates outside that pattern become impossible.

"X‑Wing is a candidate that, within 2 rows, only appears in 2 columns… it's not just a rectangle of cells you draw anywhere"

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Beyond the Basics: When Things Get Fancier

• Finned X‑wing: If one of the "corner" cells has extra candidates (a "fin"), you can analyze both possibilities (it's true vs. false) and eliminate candidates that fail in both scenarios.
• Sashimi X‑wing: A distorted version where one corner doesn't align exactly - but the logic still applies through testing both configurations.

Both are powerful next‑level moves once you're comfy spotting classic X‑wings.

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Why X-Wing Matters

Once you internalize this pattern, your solving flow becomes smoother and more strategic. X‑wings help prune the candidate field in tricky mid‑to‑hard puzzles, and they lay the groundwork for even tougher "fish" techniques like swordfish, which is just a 3‑row/column version of X‑wing.

They're not just for puzzle show-off-ing - they genuinely speed up solving by forcing logic onto often messy sections of a grid.

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Practice Tips

• After notes and singles stop working, shift your focus — scan all digits for 2-candidate rows or columns.
• Use highlighting or shading if you can — it makes spotting rectangles much easier.
• Once the pattern is familiar, you'll start seeing X-Wing setups automatically.

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Wrap-Up

The X-wing is your first "fish" pattern - a smart, logical shortcut that lets you eliminate candidates from a distance, using only alignment and candidate counts. It's elegant, it's satisfying, and once you see one, your solver's instinct kicks into gear.

Ready to fly further? Next up: Swordfish extends X-Wing to three rows and columns, or try XY-Wing for a different elimination approach.

Frequently Asked Questions

What is an X-Wing in Sudoku?

An X-Wing is a candidate elimination pattern. If one digit appears in exactly two cells in two rows (or two columns), and those cells align in the same columns (or rows), you can eliminate that digit from other cells in those columns (or rows).

Is X-Wing a beginner or advanced Sudoku technique?

X-Wing is usually an early advanced technique. Most players learn it after naked singles, hidden singles, and naked pairs.

How do I know an X-Wing is valid?

The pattern is valid only when each of the two rows (or columns) has exactly two candidates for the target digit, and they align perfectly. If one row has a third candidate for that digit, it is not a clean X-Wing.

What can I eliminate with an X-Wing?

Eliminate the target digit from other unsolved cells in the two aligned columns (or rows). Do not remove candidates from the four X-Wing corner cells.

What should I learn after X-Wing?

A common next step is Swordfish, which extends the same fish logic to three rows and columns. You can also study Finned X-Wing and XY-Wing for more advanced elimination patterns.

Browse all techniques in our complete strategy guide.

Related Strategies

Build your X-Wing skills on this foundation:

• Swordfish (Expert) - next technique
• Finned X-Wing (Expert)
• XY-Wing
• Naked Singles - Master this first
• Hidden Singles - Essential building block
• Naked Pairs - Natural progression to X-Wing
• Pointing Pairs - Intermediate bridge technique

Practice X-Wing

• Printable Expert Sudoku

Ready to go deeper? Learn about the XY-Wing technique next.

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