Mirrored from Sudopedia, the Free Sudoku Reference Guide


The cell is the smallest element of a Sudoku grid. It can contain only a single digit.


Naming Conventions

There are several cell naming conventions. Most of them use the row and column for identification. The most widely used format is rncn, where the cells are named according to the following lay-out:

|r1c1 r1c2 r1c3|r1c4 r1c5 r1c6|r1c7 r1c8 r1c9|
|              |              |              |
|r2c1 r2c2 r2c3|r2c4 r2c5 r2c6|r2c7 r2c8 r2c9|
|              |              |              |
|r3c1 r3c2 r3c3|r3c4 r3c5 r3c6|r3c7 r3c8 r3c9|
|r4c1 r4c2 r4c3|r4c4 r4c5 r4c6|r4c7 r4c8 r4c9|
|              |              |              |
|r5c1 r5c2 r5c3|r5c4 r5c5 r5c6|r5c7 r5c8 r5c9|
|              |              |              |
|r6c1 r6c2 r6c3|r6c4 r6c5 r6c6|r6c7 r6c8 r6c9|
|r7c1 r7c2 r7c3|r7c4 r7c5 r7c6|r7c7 r7c8 r7c9|
|              |              |              |
|r8c1 r8c2 r8c3|r8c4 r8c5 r8c6|r8c7 r8c8 r8c9|
|              |              |              |
|r9c1 r9c2 r9c3|r9c4 r9c5 r9c6|r9c7 r9c8 r9c9|

Alternatively, the rows are identified by letters. Some people skip the letter I to avoid confusing it with number 1, some also skip letter J. The last cell can therefore be either I9, J9 or K9. This is also known as the K9 format.

Here is the lay-out where the letter J is used for the last row:

| A1 A2 A3 | A4 A5 A6 | A7 A8 A9 |
| B1 B2 B3 | B4 B5 B6 | B7 B8 B9 |
| C1 C2 C3 | C4 C5 C6 | C7 C8 C9 |
| D1 D2 D3 | D4 D5 D6 | D7 D8 D9 |
| E1 E2 E3 | E4 E5 E6 | E7 E8 E9 |
| F1 F2 F3 | F4 F5 F6 | F7 F8 F9 |
| G1 G2 G3 | G4 G5 G6 | G7 G8 G9 |
| H1 H2 H3 | H4 H5 H6 | H7 H8 H9 |
| J1 J2 J3 | J4 J5 J6 | J7 J8 J9 |

In the larger Sudoku variants, two digits may be required to designate a row or column. In those cases, the lower numbers are often prefixed with a zero.

Number of Cells

There are 81 cells in a standard Sudoku grid, but not in all Sudoku Variations. Here is a list with some alternative formats with the number of cells:

16 cells
36 cells
144 cells
256 cells
625 cells
369 cells
729 cells
61 cells

Cell Status

A cell can either be empty or contain a digit. An empty cell is also known as an unsolved cell. Cells containing a digit are either given or solved.

There can be upto 9 candidates in a cell, one for each digit.

Related Terms

Belongs to
grid | house | row | column | box | intersection
between 2 and 9 candidates or 1 digit
This page was last modified 18:24, 11 October 2007.