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Naked Pairs technique in Sudoku
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Naked Pairs

Two Cells, Two Candidates, Powerful Eliminations

By Minimal Sudoku TeamLast updated:

Naked Pairs is one of the most useful intermediate Sudoku techniques. When two cells in the same row, column, or box contain exactly the same two candidates (and nothing else), those candidates must go in those cells — allowing you to eliminate them elsewhere.

Quick Summary
  • What: Two cells with exactly the same two candidates
  • Where: Both cells must be in the same row, column, or box
  • Result: Eliminate those two candidates from other cells in the shared unit
  • Difficulty: Intermediate — requires candidate notation

The Concept

Imagine two cells in a row that both contain only candidates 3 and 7. We don't know which cell gets the 3 and which gets the 7, but we do know that these two cells will "use up" both the 3 and 7 for that row.

This means no other cell in the row can contain 3 or 7 — we can eliminate them!

The Golden Rule

👥 Naked Pair Rule
When two cells in the same unit (row, column, or box) contain exactly the same two candidates and no other candidates, eliminate those two candidates from all other cells in that unit.

How to Find Naked Pairs

1

Look for bi-value cells

Scan the grid for cells containing exactly two candidates. These are "naked" — their candidates are fully visible.
2

Find matching cells in the same unit

When you find a bi-value cell (e.g., candidates 4 and 8), look in its row, column, and box for another cell with the same candidates.
3

Verify exact match

Both cells must have exactly the same two candidates — nothing more, nothing less.
4

Eliminate from the shared unit

Remove both candidates from all other cells in the unit where the pair was found.
Units Matter
If the pair shares multiple units (e.g., same row AND same box), you can eliminate from both units!

Practical Example

Naked Pair on 3 and 7

Naked Pair example with candidates 3 and 7

In row 4, we find two cells with identical candidates:

  • R4C2: Candidates 3, 7
  • R4C8: Candidates 3, 7

These cells form a Naked Pair in row 4. One will be 3, the other will be 7 — we just don't know which yet.

Eliminations
Remove 3 and 7 from all other cells in row 4 (R4C1, R4C3, R4C4, etc.).

These eliminations might create Naked Singles or enable other techniques!

Why It Works

The logic is simple but powerful:

Row 4:
│ ? │[3,7]│ ? │ ? │ ? │ ? │ ? │[3,7]│ ? │

Either: Cell 2 = 3, Cell 8 = 7
   Or: Cell 2 = 7, Cell 8 = 3

Either way: 3 and 7 are "claimed" by these cells!

Naked Triples & Quads

The Naked Pair concept extends to larger groups:

Naked Pair

2 cells, 2 candidates

Naked Triple

3 cells, 3 candidates

Naked Quad

4 cells, 4 candidates

Triples Don't Need All Three
A Naked Triple doesn't require each cell to have all 3 candidates. For example, cells with (1,2), (2,3), and (1,3) form a valid Naked Triple for candidates 1, 2, 3.
Naked Triples & QuadsIntermediate

Naked Triples & Quads

Learn the extended versions of Naked Pairs for more complex situations.

Detection Tips

Scan for Bi-Value Cells
Bi-value cells (exactly 2 candidates) are the building blocks of Naked Pairs. When you spot one, immediately check if there's a matching cell in the same row, column, or box.
Double-Check Shared Units
If two cells share both a row and a box (like R1C1 and R1C3), you can eliminate from BOTH the row AND the box.
Chain Reactions
After eliminating candidates, check if any cells become Naked Singles or if new Naked Pairs form. One Naked Pair often leads to another!

Related Techniques

Naked Sets Family

👥Naked Triples & Quads🔍Hidden Pairs

Related Techniques

👉Pointing Pairs✏️Snyder Notation✈️X-Wing