Naked Pairs Strategy

When two cells in a unit contain exactly the same two candidates, those candidates can be eliminated from every other cell in that unit.

Difficulty (First elimination)
Intermediate
Cells in pattern (Same unit)
2
Shared candidates (Identical lists)
2
Cells cleared (Up to 7 in a unit)
7

What Is a Naked Pair?

A Naked Pair is formed when two cells within the same unit (row, column, or 3x3 box) each contain exactly two candidates, and those candidates are the same in both cells. For example, if cell A has candidates [4, 9] and cell B in the same row also has candidates [4, 9], they form a Naked Pair.

The logic is straightforward: one of these cells must contain 4 and the other must contain 9 (or vice versa). Therefore, no other cell in that row can contain 4 or 9. You can safely remove 4 and 9 from the candidate lists of all other cells in the shared unit. This elimination frequently creates new Naked Singles or Hidden Singles.

The concept extends naturally to Naked Triples (three cells, three candidates) and Naked Quads (four cells, four candidates). Understanding pairs makes these extensions intuitive. Learn more Sudoku terms in our glossary.

How to Apply Naked Pairs: Step-by-Step

  1. Fill in pencil marks - Ensure every empty cell has its candidates noted. Pencil marks are essential for spotting pairs - without them, you are relying purely on memory.
  2. Scan for cells with exactly two candidates - Look through each row, column, and box for cells that contain exactly two candidate numbers. These are your potential pair members.
  3. Find matching pairs - Check if any two cells in the same unit share the exact same two candidates. Both cells must have the same two numbers and nothing else.
  4. Eliminate from other cells - Remove both pair candidates from all other cells in the shared unit. If the pair is in a row, eliminate from other row cells. Same logic applies to columns and boxes.
  5. Check for cascading eliminations - After removing candidates, look for new singles or additional pairs that may have been revealed. One elimination often leads to another.

When to Use Naked Pairs

Naked Pairs become essential when Naked Singles and Hidden Singles alone are not enough to make progress. This typically happens in medium Sudoku puzzles and above.

If you have filled in all obvious singles and the puzzle stalls, scan for Naked Pairs as your next step. They are one of the most rewarding intermediate techniques because the elimination pattern is easy to understand and the results are often immediate. For more techniques, visit our complete strategy guide or review how to play Sudoku.

Difficulty Level & Puzzle Types

Naked Pairs is classified as an intermediate-level technique. It bridges the gap between beginner singles strategies and more advanced pattern-recognition methods.

Easy

Rarely needed - singles are usually sufficient

Medium

Frequently needed - a key technique for medium puzzles

Hard

Regularly used - combines with other intermediate methods

Expert

Part of the toolkit - used alongside advanced techniques

Tips for Mastering Naked Pairs

  1. Always maintain complete and accurate pencil marks. Naked Pairs are virtually impossible to spot without notation.
  2. Focus on units (rows, columns, boxes) that have many filled cells - the remaining empty cells have fewer candidates, making pairs easier to identify.
  3. Remember that a cell involved in a Naked Pair must have exactly two candidates, no more. If it has three candidates, it might be part of a Naked Triple instead.
  4. After making eliminations, always re-scan for singles. The primary goal of Naked Pairs is to create new singles that let you place numbers.

Frequently Asked Questions

What is a Naked Pair in Sudoku?

A Naked Pair occurs when two cells in the same row, column, or 3x3 box contain exactly the same two candidates and no other candidates. Because those two numbers must go in those two cells (in some order), they can be eliminated from all other cells in that unit.

How does a Naked Pair differ from a Hidden Pair?

In a Naked Pair, the two cells contain ONLY the pair candidates (e.g., {3,7} and {3,7}). In a Hidden Pair, the two cells may contain additional candidates, but two specific numbers are limited to only those two cells within the unit. Both result in eliminations, but they are identified differently.

Can a Naked Pair span across different units?

A Naked Pair applies within a single unit - one row, one column, or one box. The two cells must share at least one common unit. If two cells with the same candidates are in different rows, columns, and boxes, they do not form a Naked Pair.

What happens after I find a Naked Pair?

Once you identify a Naked Pair, remove those two candidates from all other cells in the shared unit. This often reveals new Naked Singles or Hidden Singles, allowing you to make further progress on the puzzle.

How common are Naked Pairs in Sudoku puzzles?

Naked Pairs are quite common in medium and hard puzzles. They are one of the most frequently used intermediate techniques. Easy puzzles rarely require them, but medium-difficulty puzzles often need at least one pair-based elimination to solve.

Related Techniques

Related Glossary Terms

View full glossary

Practice by Difficulty

See it in action: a Naked Pair

3
7
3
7
1
3
7
9
2
8
2
3
7
8
1
9
1
2
3
7
8
2
8
2
3
7
9

Look at row 1. Cells C1 and C2 each have only two possible digits: 3 and 7.

Step 1 of 4 — full interactive demo available with JavaScript enabled

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