Glossary of Sudoku - Grid Layout and Puzzle Terms

Grid Layout and Puzzle Terms

A Sudoku grid has 9 rows, columns and boxes each having 9 cells. The full grid has 81 cells. Cells are commonly called squares, but in technical descriptions the term square is avoided since the boxes and grid are also squares. Boxes are also known as blocks or zones. Three vertically stacked blocks make a stack. Three horizontally connected blocks make a band. A chute is either a band or a stack. A grid has three bands, three stacks and six chutes.

The use of the boxes to partition the grid can be generalized to other equal-sized partition shapes, in which case the sub-areas are known as regions, zones, subgrids, or nonets. See Variants below. In some cases the regions are only equal sized, not equal shaped.

Rows, columns and regions are collectively referred to as units or scopes, of which the grid has 27. The One Rule can then be compactly stated as: "Each digit appears once in each unit".

Size refers to the size of a puzzle or grid. Often a composite row × column designation is used, e.g. size 9×9. In technical discussions size may mean the number of cells, e.g. 81. Since the number of cells in a region must be the side dimension of the square grid, e.g. nine cells per block for a 9×9 grid, it is convenient to just use the region size, e.g. 9.