Advanced Sudoku Strategy
Two-String Kite Sudoku: How to Find and Use the Technique
Learn how a row strong link and a column strong link connect through a 3×3 box to eliminate a candidate without guessing.
Two Strong Links, One Elimination
One strong link in a row, one in a column, and connecting ends sharing a box. At least one free end must be true.
What Is a Two-String Kite in Sudoku?
A Two-String Kite is an advanced technique using two strong links for the same candidate: one in a row and one in a column. A strong link means the candidate appears in exactly two cells in that unit. One endpoint of each link sees the other endpoint inside a shared 3×3 box. These are the connecting ends; the other endpoints are the free ends. At least one free end must be true.
How the Two-String Kite Works
If both free ends were false, both connecting ends would have to be true because of the strong links. But the connecting ends see each other in a 3×3 box, so they cannot both contain the same digit. Therefore at least one free end must contain that digit.
When Should You Look for a Two-String Kite?
Try this technique in Hard and Expert Sudoku when singles, pairs, and locked candidates stop making progress. Turn on Notes and scan one candidate at a time for rows and columns with exactly two remaining positions.
Two-String Kite vs. Skyscraper
A Two-String Kite uses a row strong link and a column strong link connected through a box. A Skyscraper normally uses two parallel row links or two parallel column links.
Common Mistakes
Do not mix candidate numbers. Confirm each selected row or column has exactly two positions for the candidate. Confirm the connecting ends see each other inside a box. The elimination target must see both free ends. Do not remove the candidate from the kite endpoints themselves.
How to Find a Two-String Kite: Step by Step
Choose One Candidate
Focus on one digit from 1 to 9.
Find a Row Strong Link
Look for exactly two positions for that digit in a row.
Find a Column Strong Link
Find exactly two positions for the same digit in a column.
Connect Through a Box
One end of each strong link must see the other inside a 3×3 box.
Identify the Free Ends
The two remaining endpoints are the free ends.
Find the Target
Find another cell that sees both free ends and contains the candidate.
Eliminate and Rescan
Remove the candidate from the target and look for follow-up moves.
Related Sudoku Learning Pages
Frequently Asked Questions
What is a Two-String Kite?
A pattern using one row and one column strong link for the same digit, connected through a box.
What is a strong link?
A candidate has exactly two possible positions in a row or column, so one of them must be true.
How is it different from Skyscraper?
Two-String Kite uses a row link and a column link; Skyscraper uses two parallel links.
Where can you eliminate a candidate?
From a different cell that sees both free ends.
Does it use multiple numbers?
No. Both links and the elimination use the same digit.
Practise Two-String Kite Sudoku
Open a Hard or Expert puzzle, turn on Notes, and look for a row-column pair of strong links connected through a box.