Naked Pairs
Two cells in a unit that share exactly the same two candidates — eliminate those digits everywhere else in the unit.
What is Naked Pairs?
A Naked Pair occurs when exactly two cells within the same row, column, or 3×3 box each contain exactly the same two candidates and no others. For example, if Cell A shows only [3, 7] and Cell B (in the same row, column, or box) also shows only [3, 7], these two cells form a Naked Pair. The logic is airtight: one cell must contain 3 and the other must contain 7 — we just don't know which is which yet. But because both digits are "used up" by this pair, no other cell in the unit can contain either 3 or 7. This means those digits can be safely removed from all other candidates in the shared unit. This elimination often cascades into new Singles or reveals further pairs, making Naked Pairs one of the most productive intermediate techniques. Note that the cells forming the pair do not need to be adjacent; they just need to be in the same unit. Also important: the two cells must each have exactly two candidates — if either has three or more, it is not a Naked Pair (though it might be part of a Naked Triple).
When to Use Naked Pairs
Apply Naked Pairs when all basic Singles (Naked and Hidden) and scanning techniques are exhausted and the puzzle has stalled. This typically happens in Medium and Hard puzzles where a full candidate grid has been established. Look carefully at each row, column, and box for cells with exactly two candidates. The technique is most rewarding in units that are nearly complete (5+ digits placed) where the pair's digits need to be determined. When checking each unit, don't just look for exact matching pairs visually — methodically compare the candidates of every 2-candidate cell in the unit with every other 2-candidate cell. Naked Pairs can also appear alongside Hidden Pairs in the same unit, so after applying one, recheck for the other.
How to Apply Naked Pairs — Step by Step
- 1
Establish a complete candidate grid
Before searching for Naked Pairs, ensure every empty cell on the board has been annotated with its complete, up-to-date set of candidate digits. A candidate grid is essential for spotting pairs. Use pencil marks — small numbers written in each cell's corners to represent valid candidates.
- 2
Find cells with exactly two candidates
Scan each row, column, and box. Look specifically for cells that contain exactly two candidates and no more. These are the only cells that can participate in a Naked Pair. Cells with one candidate are Naked Singles (place them first). Cells with three or more candidates are not part of a Naked Pair.
- 3
Look for matching pairs
Compare each 2-candidate cell against all other 2-candidate cells in the same unit. If two cells in the same row, column, or box have the exact same two candidates (e.g., both cells show [3, 7] and nothing else), you have found a Naked Pair. The matching must be exact — [3, 7] paired with [3, 7], not [3, 7] with [3, 7, 9].
- 4
Eliminate from the unit
Remove both paired candidates (3 and 7 in the example) from the candidates of all other cells in the shared unit. This is the elimination step. Every other cell in that row, column, or box that currently shows 3 or 7 as a candidate loses those candidates.
- 5
Scan for new singles and patterns
After eliminating, immediately re-scan the affected unit (and any other units containing the modified cells) for new Naked Singles, Hidden Singles, or additional Naked Pairs that have been created by the eliminations.
💡 Pro Tip
Naked Pairs work in any unit — rows, columns, and boxes. Check all three for the same pair of cells. A powerful strategy is to look for Naked Pairs in units where many cells are already filled (say, 6–7 cells placed), because the remaining empty cells are fewer, making it easier to spot pairs visually. Also, after finding a Naked Pair in one unit, check whether the same cells form a pair in an intersecting unit too — this can trigger additional eliminations in that second unit.
Practice Naked Pairs Now
Put this technique to the test on a live puzzle. The Practice Mode lets you work through real examples with candidate marking.