A W-wing is a Sudoku elimination technique that is easier to spot than other patterns like the [X-wing](https://sudokubliss.com/guides/X-Wing-technique) or [Y-wing](https://sudokubliss.com/guides/Finding-Y-Wing-Styles). It's a chain that consists of four cells and meets the following criteria:

* The first and last cells in the chain must be **identical bi-value cells** containing candidates x and y. These cells cannot share a row, column, or block.
* The middle two cells must be a **conjugate pair** with a strong link between either x or y. A conjugate pair means that they are the only two cells within the same unit that contain the x or y candidate number.
* Each of the middle cells must **share a unit with one** of the bi-value cells.

This creates a logic chain that may help you eliminate candidates in cells that both the bi-value cells can see. Using the W-wing can help you solve all types of [Sudoku puzzles](https://sudokubliss.com/), from [hard](https://sudokubliss.com/hard) to [evil](https://sudokubliss.com/evil). In this Sudoku tutorial, we'll explain how to identify W-Wings and share examples.

## How to Find W-Wings

W-Wings are relatively easy to spot, making them a good technique to learn and practice if you're just beginning to improve your understanding of [Sudoku strategies](https://sudokubliss.com/guides/Sudoku-Tips-and-Strategies). However, they don't always lead to eliminations if the chain doesn't follow the logic described below.

![Sudoku W-Wing example](https://sudokubliss.com/content-uploads/w-wing-example-1-step-3.webp)  
  
Use these steps to help you find a W-wing in your Sudoku puzzle.

1. **Identify two bi-value cells with the same candidates (x and y).** These cells should not see each other, meaning that they are not in the same row, column, or block.
2. **Find two more cells with a strongly linked conjugate pair of x or y.** Each one of these linked cells should be visible to one of the bi-value cells. Remember, a strongly linked pair means that a specific candidate number only appears twice within a unit, so if one is false, then the other must be true.
3. **Analyze the logic chain. The strongly linked pair is made of candidate x or y.** In this example we'll use x. If x is true in one cell of the strongly linked pair, it must be false in the other cell of the strongly linked pair. Therefore, x can't be true in one of the bi-value cells, making one of the bi-value cells y, so any cell(s) that sees both bi-value cells cannot be Y.
4. **Eliminate candidates.** Because y must be true in one bi-value cell or the other, it cannot exist in any cells that see both bi-value cells. If it does, you can eliminate it as a candidate in those cells.

## W-Wing Examples

Now that you have the general idea of how the technique is used, work through these examples with us to solidify your understanding.

### W-Wing Example 1

1. **A2 and I8 both have identical bi-value candidates** (3, 7) in cells that don't see each other.
![Sudoku W-Wing example 1 step 1](https://sudokubliss.com/content-uploads/w-wing-example-1-step-1.webp)  
  
2. **Column E has a strongly linked conjugate pair of 3s** in E2 and E8\. E2 sees one of the bi-value cells (A2) and E8 sees the other bi-value cell (I8). This forms a linked chain.
![Sudoku W-Wing example 1 step 2](https://sudokubliss.com/content-uploads/w-wing-example-1-step-2.webp)  
  
3. **Now you can use logic to determine if candidate elimination is possible.**
  * If E2 is 3, then E8 is not 3\. Therefore A2 is 7.
  * If E8 is 3, then E2 is not 3\. Therefore I8 is 7.
  * Either way, one bi-value cell must be 7.

Because one bi-value must be 7, 7 candidates can be eliminated in any cells that see both bi-value cells. In this case, the 7 candidate can be eliminated in I2.

![Sudoku W-Wing example 1 step 3](https://sudokubliss.com/content-uploads/w-wing-example-1-step-3.webp)  
  
### W-Wing Example 2

1. **A5 and C8 both have identical bi-value candidates** (2, 4) in cells that don't see each other.
![Sudoku W-Wing example 2 step 1](https://sudokubliss.com/content-uploads/w-wing-example-2-step-1-v2.webp)  
  
2. **The top left block has a strongly linked conjugate pair of 4s** in B2 and C2\. A2 sees one of the bi-value cells (A5) and C2 sees the other bi-value cell (C8).
![Sudoku W-Wing example 2 step 2](https://sudokubliss.com/content-uploads/w-wing-example-2-step-2.webp)  
  
3. **The following logic confirms that elimination is possible.**
  * If A2 is 4, then C2 is not 4\. Therefore A2 is 2.
  * If C2 is 4, then A2 is not 4\. Therefore C8 is 2.
  * Either way, one bi-value cell must be 2.

Because one bi-value cell must be 2, the 2 candidates can be eliminated in any cells that see both bi-value cells (A7, A8, and A9). Since there are 2s in A7 and A9, they can be eliminated.

![Sudoku W-Wing example 3 step 2](https://sudokubliss.com/content-uploads/w-wing-example-2-step-3.webp)  
  
Ready to see if you spot a W-Wing in a Sudoku puzzle? We offer hundreds of [sudoku puzzles online for free](https://sudokubliss.com/)!