Nonogram Rules

Each number represents the length of one uninterrupted group of filled cells.

For example, the clue:

5

means that the line contains one group of exactly five consecutive filled cells.

The clue:

3 2

means that the line contains:

1. A group of three filled cells.
2. At least one empty cell.
3. A group of two filled cells.

The groups must appear in the same order as the clues.

For example:

1 4 2

means that the line contains a group of one filled cell, followed later by a group of four filled cells, and finally a group of two filled cells. There must be at least one empty cell between consecutive groups in a standard black-and-white Nonogram.

Cell Symbols

The following symbols are commonly used while solving:

• ■ — a cell that must be filled.
• × — a cell that must remain empty.
• · — a cell that has not yet been determined.

Marking empty cells is just as important as filling cells. Empty cells limit the possible positions of the remaining blocks and often create the next logical step.

Important Rules

1. Every clue represents one continuous block of filled cells.
2. Blocks must appear in the order shown.
3. In black-and-white Nonograms, separate blocks must have at least one empty cell between them.
4. A block may begin at the first cell or end at the last cell.
5. Empty cells may appear before the first block and after the last block.
6. Every row and column must satisfy all its clues.
7. A properly constructed puzzle should be solvable logically without blind guessing.

How to Read Nonogram Clues

Consider a line containing ten cells.

Example 1: Single Block

The line contains one continuous group of four filled cells.

Example 2: Multiple Blocks

There is a group of three cells, at least one empty cell, and then a group of two cells.

Example 3: Exact Fit

Because the blocks and required spaces fill the entire line, every cell can be determined immediately.

Step-by-Step Solving Example

Consider this simple 5×5 Nonogram.

Step 1: Find Complete Lines

Row 3 has the clue 5 in a five-cell grid. Therefore, every cell in Row 3 must be filled.

Column 3 also has the clue 5, so every cell in Column 3 must be filled.

Step 2: Complete the Clues of 1

Row 1 has the clue 1, and its centre cell is already filled. Therefore, every other cell in that row must be empty.

The same applies to Row 5.

Column 1 also has the clue 1, and its centre cell is filled. All other cells in that column must be empty.

The same applies to Column 5.

Step 3: Complete the Remaining Lines

Rows 2 and 4 each have the clue 3. Because the first and last cells are already marked empty, the three centre cells must be filled.

The completed Nonogram reveals a diamond-shaped picture.