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Claiming Pairs technique in Sudoku
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Claiming Pairs

When Lines Claim Candidates in a Box

By Minimal Sudoku TeamLast updated:

Claiming Pairs (also called "Box/Line Reduction") is the mirror of Pointing Pairs. When a candidate on a row or column is confined to one box, the line "claims" that candidate — eliminating it from other cells in the box.

⚡Quick Summary
  • What: A candidate on a row/column appears only in cells within one box
  • Result: Eliminate that candidate from other cells in the box (outside the line)
  • Claiming Pair: Candidate in exactly 2 cells on the line within the box
  • Claiming Triple: Candidate in exactly 3 cells on the line within the box

The Concept

Every row and column must contain each digit 1-9. If we look at where a specific digit can go on a row, sometimes all possible cells fall within one box.

When this happens, the row "claims" that candidate for its intersection with the box. This means the candidate cannot appear elsewhere in that box — we can eliminate it from cells outside the row (but still in the box).

The Golden Rule

📍 Claiming Pair Rule
If a candidate on a row (or column) can only appear in cells that are all within the same box, eliminate that candidate from all other cells in that box (the cells not on the row/column).

How to Find Claiming Pairs

1

Pick a row or column

Choose a line to analyze.
2

Pick a candidate

Choose a digit (1-9) that hasn't been placed on this line yet.
3

Find all possible cells

Identify every cell on the line where this candidate could go.
4

Check box confinement

Are all possible cells in the same 3×3 box? If yes, you have a Claiming Pair (2 cells) or Claiming Triple (3 cells).
5

Eliminate from the box

Remove the candidate from all other cells in that box (the cells not on your line).

Practical Example

Claiming Pair on Digit 6

Claiming Pair example with digit 6

On row 5, let's find where digit 6 can go:

  • R5C1: 6 in same box → eliminated
  • R5C2: 6 in same box → eliminated
  • R5C3: 6 in same column → eliminated
  • R5C4: No conflicts → possible
  • R5C5: No conflicts → possible
  • R5C6: 6 in same column → eliminated
  • R5C7-C9: Various conflicts → eliminated

The candidate 6 can only go in R5C4 or R5C5 — both in Box 5!

Elimination
Eliminate 6 from all other cells in Box 5 (R4C4, R4C5, R4C6, R6C4, R6C5, R6C6). Row 5 claims the 6 for Box 5.

Claiming vs Pointing

Claiming Pairs and Pointing Pairs are mirror techniques — same logic, different directions:

👉 Pointing Pair

Start in a box

Candidate confined to one line within the box

→ Eliminate from the line (outside box)

📍 Claiming Pair

Start on a line

Candidate confined to one box on the line

→ Eliminate from the box (outside line)

Together, these form the "Locked Candidates" family — foundational intermediate techniques.

Pointing Pairs & TriplesIntermediate

Pointing Pairs & Triples

The mirror technique: when box candidates point to line eliminations.

Detection Tips

Scan Lines with Few Options
Lines with many filled cells have fewer candidate positions. If a digit can only go in 2-3 spots on a nearly-full row, check if they're all in one box.
Check After Eliminations
When you eliminate candidates (from any technique), check if the remaining positions on affected lines are now confined to one box.
Both Directions
Always check both Pointing and Claiming when analyzing box/line intersections. They often appear together in the same puzzle area.

Related Techniques

Locked Candidates

👉Pointing Pairs🔒Locked Candidates Overview

Related Techniques

👥Naked Pairs👀Hidden Pairs✈️X-Wing