Difficulty
Medium to Hard
This is where X-Wing normally sits in a human solving path.
Sudoku technique guide
X-Wing Sudoku Technique
An X-Wing is a four-corner pattern for one candidate across two rows or columns. This guide explains the idea in plain English, when to look for it, and the common mistake to avoid.
At a glance
Family
Fish techniques
It belongs to the fish techniques group of Sudoku logic.
Main action
Usually remove candidates
Most technique moves reduce notes first. That often reveals a simpler placement afterwards.
What is X-Wing?
An X-Wing is a four-corner pattern for one candidate across two rows or columns.
The important thing is that this is logic, not guessing. You are using the current candidates to prove that a number must either go in one place, or cannot stay in another place.
In SudoSketch, this technique is designed to work with notes and Coach highlighting, so the key cells and removal cells can be shown clearly.
How X-Wing works
- Focus on one candidate only.
- Find two rows or columns where that candidate appears in exactly two matching positions.
- The four cells form a rectangle, so remove the candidate from the other cells in the matching lines.
Try X-Wing in the SudoSketch Learn Arena
Interactive Logic Theatre
Loading X-Wing lesson...
When to look for it
Look for X-Wing after easier moves have stopped working. First check for naked singles, hidden singles, locked candidates and simple pairs. If those do not move the puzzle forward, this technique may be worth checking.
For learning, do not try to scan for every advanced technique at once. Pick one method, understand the shape, and practise spotting that one pattern.
Common mistake
The candidate must line up cleanly in two rows or two columns. A messy rectangle is not an X-Wing.
If you are unsure, rebuild the candidates first. Bad notes create bad logic, and Sudoku will absolutely punish you for it like a tiny spreadsheet goblin.
X-Wing FAQ
What is X-Wing in Sudoku?
An X-Wing is a four-corner pattern for one candidate across two rows or columns.
When should I look for X-Wing?
Look for X-Wing after simpler moves such as singles, locked candidates and obvious pairs have stopped helping.
Can SudoSketch Coach help with X-Wing?
Yes. SudoSketch Coach can highlight candidate patterns and explain the next logical step when a X-Wing move is available.