Pointing Pairs

Medium techniques · Updated 9 July 2026

Short answer: a pointing pair is when a shape's only spots inside a box all lie on one row or one column. The shape must land somewhere in the box, so it must land on that line here — which means it can be struck from the same line everywhere outside the box. It is one half of the "locked candidates" idea.

What a pointing pair looks like

Take a box and pick a shape it still needs. Mark every cell in the box where that shape could still go. If those cells all share one row or one column, the shape is "pointing" along that line — it is trapped on that line within the box, so the line outside the box can't use it.

Inside the highlighted box, the triangle fits only two cells — and both sit in the same column. So the triangle must be in the box on that column, and can be eliminated from that column outside the box.

The pair "points" out of the box and down the line. You place nothing — you remove the shape from the rest of that row or column, which often frees a single further along.

How to use a pointing pair

  1. Choose a box and a shape. Pick a 3×3 box and one shape it still needs to place.
  2. Mark where the shape can go. Note every empty cell in the box that could still take that shape.
  3. Check for a shared line. If all those cells sit in one row, or one column, the shape is locked to that line inside the box — a pointing pair (or triple).
  4. Eliminate along the line. Strike that shape from every cell on the same row or column outside the box. It has to be inside the box, so it cannot be elsewhere on the line.

Pointing pairs are the box-to-line half of locked candidates. The reverse — a shape trapped inside one box because a whole line points into it — is box/line reduction. They are the same rule read in opposite directions.

Pointing pair vs box/line reduction

Both are "locked candidates". A pointing pair starts in the box: the shape is stuck on one line within it, so you clear the line outside. Box/line reduction starts in the line: the shape is stuck in one box along it, so you clear the rest of the box. Look at the box first for pointing, the line first for reduction.

Frequently asked questions

What is a pointing pair in sudoku?

A pointing pair is a shape whose only possible cells inside one box all lie on a single row or column. Because the shape must go somewhere in the box, it must go on that line here — so it can be eliminated from the rest of that row or column outside the box.

What is the difference between a pointing pair and a pointing triple?

Only the count. If the shape is confined to two aligned cells in the box it is a pointing pair; if three aligned cells, a pointing triple. The elimination along the line works exactly the same way.

Does a pointing pair solve a cell?

No — it removes a candidate from the line outside the box. That elimination often exposes a hidden single or another move, which is where the actual placement comes from.

Is a pointing pair the same as locked candidates?

It is one of the two locked-candidate patterns. "Locked candidates, type 1" is the pointing pair (box points to a line); "type 2" is box/line reduction (line locks a shape into a box).