Hidden Pair in Sudoku: How to Spot It
Learn how Hidden Pairs work in Sudoku, why they are harder to see than Naked Pairs, and how to clean up candidates.
Guided example
See the Hidden Pair on this board
Read this as one teaching unit: first identify the active unit, then the marked pattern cells, then the candidates removed or maintained.
Quick answer
A Hidden Pair in Sudoku is when two candidates appear only in the same two cells of a row, column, or box. Those two cells must contain those two numbers, so all other candidates can be removed from those cells.
How to spot it
Follow the board in order
- 1 Choose one row, column, or box and scan by number positions.
- 2 Pick two numbers and check where each can appear.
- 3 If both numbers are limited to the same two cells, they form a Hidden Pair.
- 4 Remove all other candidates from those two cells.
What is a Hidden Pair?
A Hidden Pair happens when two numbers can only fit in the same two cells of a row, column, or box. The pair is “hidden” because those cells may also contain other candidates.
When to look for it
Look for Hidden Pairs when a unit feels crowded and obvious eliminations are not available. Instead of scanning cells, scan where each number can go.
Example walkthrough
This walkthrough uses a real hard app puzzle tagged Hidden Pair. In row 6, digits 2 and 4 can only appear in the two blue cells, r6c2 and r6c8. Because those two digits are reserved there, unrelated candidates are removed from those same two cells.
Why the cleanup works
If 2 and 4 can only appear in two cells in a unit, those two cells must eventually contain 2 and 4. Any other candidates in those cells are impossible and can be removed.
Hidden Pair vs. Naked Pair
A Hidden Pair is found by looking at where two numbers can go. The pair may be hidden among extra candidates.
A Naked Pair is found by looking at the cells first. The two cells already contain only the same two candidates.
Common mistake
Do not remove 2 and 4 from the Hidden Pair cells. With a Hidden Pair, you remove the extra candidates from the pair cells instead.
FAQ
What is a Hidden Pair in Sudoku?
A Hidden Pair is two numbers that can only go in the same two cells within a row, column, or box.
How is Hidden Pair different from Naked Pair?
A Naked Pair is visible as two identical two-candidate cells. A Hidden Pair may be inside cells with extra candidates, so you find it by tracking positions for two numbers.
What do you eliminate with a Hidden Pair?
You remove all other candidates from the two pair cells.
Is Hidden Pair harder than Naked Pair?
Usually yes, because the pattern is hidden among extra candidates instead of appearing as two clean two-candidate cells.
In this lesson
- Board example: see the pattern first.
- Walkthrough: connect each highlight to the rule.
- FAQ: check edge cases after the move is clear.
Practice this technique in Sudoku Coach
Read the pattern, then practice it step by step with guided hints that explain why the move works.
Related Sudoku techniques
Locked Candidates in Sudoku: How to Spot Them
Learn the Locked Candidates Sudoku technique: when candidates are trapped in one line or one box and can be removed elsewhere.
Naked Pair in Sudoku: How to Spot It
Learn how Naked Pairs work in Sudoku, when to look for them, and how to remove candidates safely.
Hidden Single in Sudoku: How to Spot It
Learn the Hidden Single Sudoku technique: when a number has only one possible position in a row, column, or box.