Boxes are the 3×3 regions that make Sudoku unique among logic puzzles.
Understanding the Concept
A box (also called a block or region) is a 3×3 section of the Sudoku grid.
There are 9 boxes in total, arranged in a 3×3 pattern.
Each box contains 9 cells and must have all digits 1-9 when complete.
Boxes often have thicker borders to make them visually distinct.
The box constraint is what makes Sudoku different from similar puzzles.
Boxes are numbered 1-9, typically from left to right, top to bottom.
Examples
Box 1 (Top-Left)
Box 1 occupies the top-left corner. It contains cells from rows 0-2 and columns 0-2.
5
3
7
6
1
9
5
9
8
6
8
6
3
4
8
3
1
7
2
6
6
2
8
4
1
9
5
8
7
9
Pattern / Involved
Box 5 (Center)
Box 5 is in the center of the grid. It interacts with all surrounding boxes, making it strategically important.
5
3
7
6
1
9
5
9
8
6
8
6
3
4
8
3
1
7
2
6
6
2
8
4
1
9
5
8
7
9
Pattern / Involved
Pro Tips
- •Always check the box constraint when placing a number
- •Numbers in a box affect all cells in that box, regardless of row or column
- •Box intersections with rows and columns create powerful solving opportunities
