What Is a Nonogram?

A nonogram is a picture logic puzzle played on a rectangular grid. Your goal is to fill in the correct cells to reveal a hidden image. You solve it using only the number clues printed along the edges of the grid — no guessing required.

Nonograms go by many names depending on where you play them: Picross (Japan and Nintendo), Griddlers (Europe), Hanjie (UK puzzle magazines), and Paint by Numbers. They are all the same game.

Understanding the Clue Numbers

Each row and column has a list of numbers printed beside or above it. These numbers tell you exactly how many consecutive filled cells appear in that line — in order.

For example, a clue of 3 2 in a 10-cell row means: somewhere in the row there is a block of 3 filled cells, then at least one empty cell, then a block of 2 filled cells. The groups always appear in the order listed, left-to-right for rows and top-to-bottom for columns.

A clue of 0 means the entire row or column is empty — every cell should be marked with an X.

Your First Move: Find the Certainties

Before you touch any cell, look for lines where the answer is partially forced. This is called the overlap technique.

Imagine a row of 10 cells with a single clue of 7. The block of 7 could start at position 1, 2, 3, or 4 — but no matter where it starts, cells 4 through 7 must always be filled. Fill those in immediately. The overlap is the guaranteed area.

The formula is simple: if a clue number is larger than half the available space, there will be an overlap. The larger the clue relative to the line length, the more cells you can fill with certainty.

Marking Empty Cells

Marking empty cells with an X is just as important as filling cells. When you know a cell cannot be part of any block, mark it immediately.

X marks serve two purposes: they prevent you from accidentally filling a cell you already ruled out, and they visually narrow down where the remaining blocks can go. Skipping X marks is one of the most common beginner mistakes.

On this site, use the Mark tool (keyboard shortcut: M) to place X marks, and the Fill tool (keyboard shortcut: F) to fill cells.

Solving by Elimination

Once you have some cells filled and some marked, you can use elimination across rows and columns simultaneously.

If a column clue is 2 and you have already filled 2 consecutive cells in that column, every other cell in the column must be empty — mark them all with X. Then look at the rows those newly-marked cells belong to. Each X constrains what is possible in that row too.

This back-and-forth between rows and columns is the core loop of nonogram solving. Every deduction unlocks further deductions. Keep switching between rows and columns until the puzzle is complete.

Common Beginner Mistakes

• Filling cells without certainty. Only fill a cell when logic guarantees it must be filled. Guessing costs a life in Survival mode.
• Skipping X marks. Empty cells carry information. Mark them as you go, not after.
• Ignoring completed lines. When a row or column is fully solved, use it immediately to constrain intersecting lines.
• Forgetting the gap rule. Groups must be separated by at least one empty cell. A clue of 2 2 in 5 cells has only one valid arrangement: ■■ _ ■■.
• Working only on one axis. Always cross-reference rows and columns together, not separately.

Practice: Start with Easy Puzzles

Easy puzzles use small 5×5 to 10×10 grids with straightforward clues. They are the ideal place to practice the overlap technique and get comfortable with the fill/mark workflow before moving up to larger grids.

When you can solve Easy puzzles without using hints or making mistakes, you are ready for Medium. Medium puzzles (10×10 to 15×15) introduce more complex clue combinations and require you to hold more information in memory at once.

Start with an Easy puzzle →

Quick Reference: Core Rules

1. Each number = one consecutive block of filled cells in that line.
2. Multiple numbers in a clue are listed in the order the blocks appear.
3. There must be at least one empty cell between any two blocks.
4. A clue of 0 means the entire line is empty.
5. Every puzzle has exactly one valid solution reachable through logic.

Next Steps

Once you are comfortable with the basics, the key to improvement is speed and pattern recognition. Experienced solvers scan for overlaps, edge cells, and nearly-complete lines almost automatically.

Try working through a few puzzles each day. You will notice your solving speed increase quickly as the core techniques become second nature.

Play Nonogram Online →