Look for two cells in one unit whose candidate lists are identical and exactly two digits long. Those digits are then committed to those two cells, even though you cannot yet tell which goes where, so delete both from the rest of the row, column or box.
What Is It?
A Naked Pair occurs when two cells in the same unit (row, column, or box) each contain exactly the same two candidates, and no other candidates. We don't know which digit goes where yet, but we know for certain that these two digits will occupy these two cells. Therefore, both digits can be removed from all other cells in that unit.
The pair is called "naked" because the two candidates are fully visible. There's nothing else in the cells to obscure them. This is in contrast to a Hidden Pair, where the key digits are mixed in with other candidates.
Naked Pairs are one of the most satisfying techniques to spot. They appear regularly in Medium and Hard puzzles and often trigger a cascade of further eliminations.
How It Works
The logic is elegant. If R4C2 has candidates {3, 7} and R4C8 also has candidates {3, 7}, then one of these cells must be 3 and the other must be 7. We can't tell which is which yet, but we know both digits are accounted for.
Since 3 and 7 are "claimed" by these two cells, no other cell in row 4 can contain 3 or 7. Remove 3 and 7 from the candidate lists of every other cell in row 4.
The same logic applies if the pair shares a column or a box instead of a row. And if two cells share both a row and a box (like R1C1 and R1C3, both in box 1), you can eliminate from both the row and the box.
Critical rule: both cells must have exactly these two candidates and nothing else. If one cell has {3, 5, 7} instead of {3, 7}, it's not a Naked Pair. The cell with three candidates could be 5, which would break the pair logic.
Worked Examples
Example 1: Naked Pair in a Row
Look at row 1. After filling in pencil marks, two cells stand out: R1C3 has candidates {7, 9} and R1C6 also has candidates {7, 9}, and nothing else. This is a Naked Pair.
R1C3 and R1C6 both contain only candidates {7, 9} in row 1. This is a Naked Pair.
Since 7 and 9 must occupy R1C3 and R1C6 (in some order), neither digit can appear anywhere else in row 1. Scan the remaining empty cells.
Green circles mark the Naked Pair digits. Red circles mark where 7 and 9 will be eliminated from other cells in row 1.
Remove 7 and 9 from R1C7 and R1C9, and 9 from R1C8. After eliminating, R1C7 drops to a single candidate (6), a Naked Single. Place it and continue.
Digits 7 and 9 eliminated from R1C7, R1C8, R1C9. R1C7 is reduced to a single candidate (6), a Naked Single.
Example 2: Naked Pair in a Box
Now look at box 3 (top-right). R1C7 has candidates {4, 9} and R2C8 also has {4, 9}. These two cells form a Naked Pair within the box.
R1C7 and R2C8 both contain only candidates {4, 9} in box 3. This is a Naked Pair.
Since 4 and 9 are claimed by R1C7 and R2C8, remove both digits from all other empty cells in box 3: R1C9, R2C7, and R2C9.
Green circles mark the Naked Pair digits. Red circles mark where 4 and 9 will be eliminated from other cells in box 3.
After eliminating, R2C7 drops to a single candidate (6), a Naked Single. Notice how the pair cells don't need to share a row or column, they just need to share a unit.
Digits 4 and 9 eliminated from R1C9, R2C7, R2C9 (red strikethrough). R2C7 is reduced to a single candidate (6), a Naked Single.
Example 3: Naked Pair in a Column
In column 5, cells R5C5 and R7C5 both contain only {1, 8}.
In column 5, cells R5C5 and R7C5 both contain exactly {1, 8}. No other cell in column 5 has both of these candidates together. Since 1 and 8 must go in these two cells, eliminate 1 from R4C5 (which had {1, 3, 5}).
{1, 8} are locked in R5C5 and R7C5. Eliminate them from other cells in column 5.
Eliminated {1} from R4C5.
These are two common variations. Naked Pairs in rows and columns are easier to spot since the cells align visually. Pairs in boxes are trickier because the cells may be diagonal. Practice scanning both.
Frequently Asked Questions
How do I tell a Naked Pair from a Hidden Pair?
A Naked Pair's two cells contain those two candidates and nothing else, so the digits are fully visible. In a Hidden Pair the two digits appear in only two cells of the unit, but those cells carry extra candidates that obscure the pattern. Naked is about what the cells contain; hidden is about where the digits can go.
Does it still count if one of the two cells has a third candidate?
No. Both cells must show exactly those two candidates and nothing more. If one cell holds {3, 5, 7} while the other holds {3, 7}, the first cell could turn out to be 5, so the two digits are no longer guaranteed to occupy the two cells and the eliminations would be unsound.
Do I need to work out which digit goes in which cell?
No, and that is exactly what makes the technique work. Knowing the two digits fill the two cells in some order is enough: between them they use up both digits, so neither can appear anywhere else in the unit. Which cell takes which digit is settled later by other eliminations.
Can a Naked Pair sit in a box, or must the two cells be in a line?
A Naked Pair works in any single unit, so a box is fine and the two cells need not be aligned. Pairs inside a box are the ones most often missed, precisely because they do not form a straight line. Wherever both cells share one unit, the eliminations apply across that unit.
What if the two cells share a row and a box at the same time?
Then eliminate from both units. Two cells such as R1C1 and R1C3 sit in row 1 and in box 1, so the pair's digits can be removed from the rest of the row and from the rest of the box. Check for that overlap every time, as it is easy to clear the row and forget the box.
Nothing was solved after I applied the pair. What now?
Re-scan the units you changed. A Naked Pair's eliminations often leave another cell with a single candidate, or expose a further pair, so the technique tends to cascade. If nothing follows immediately, the shortened candidate lists still stand, and they give the next technique you try more to work with.
Key Points to Remember
- Both cells must contain exactly two candidates, and they must be the same two candidates. No extra digits allowed.
- Eliminate the pair's digits from all other cells in the shared unit (row, column, or box).
- If two cells share multiple units (like same row AND same box), eliminate from all shared units.
- Don't overlook Naked Pairs in boxes. They're easier to miss because the cells aren't in a straight line.
- A Naked Pair often triggers Naked Singles or further pairs. After making eliminations, always re-scan the affected units.
The best way to master Naked Pair is to practice spotting it in real puzzles.