How to Play Nonograms
Nonograms (also known as Picross, Griddlers, or Paint by Numbers) are logic puzzles where you reveal a hidden picture by filling cells in a grid. This guide will teach you everything you need to know.
What is a Nonogram?
A nonogram is a grid puzzle where each cell can be either filled (black) or empty (white). Your goal is to determine which cells should be filled based on numerical clues provided for each row and column.
Unlike crosswords or Sudoku, nonograms don't give you letters or digits to place. Instead, you work with visual patterns, using logic to deduce which cells form the hidden image.
Understanding Clues
The numbers along the top and left side of the grid are your clues. Each sequence of numbers describes groups of consecutive filled cells in that row or column.
Key Rules for Clues:
1.
Order matters. The groups appear in the order listed, from left to right (for rows) or top to bottom (for columns).
2.
At least one gap. There must be at least one empty cell between consecutive groups.
3.
Exact counts. A clue of "3" means exactly three consecutive filled cells, no more, no less.
4.
Empty rows/columns. If a clue is "0" or absent, the entire row or column is empty.
Example: A row with clues "2 1 3" means:
First, a group of 2 consecutive filled cells
Then at least one empty cell
Then a single filled cell
Then at least one empty cell
Finally, a group of 3 consecutive filled cells
Cell States: Filled, Empty, Unknown
Every cell starts as unknown (blank). As you solve the puzzle, you'll mark cells as either:
Filled (Black)
These cells are part of the hidden picture. Mark them when you're certain they must be filled based on the clues.
Empty (Crossed)
These cells are definitely not part of the picture. Marking them with a cross helps you see the remaining space and avoid mistakes.
Pro tip: Always mark cells you know are empty. This dramatically speeds up solving by making the remaining possibilities clearer.
Worked Example: Solving a 5×5 Nonogram
Let's solve a simple puzzle step by step to see how the logic works. Here's our starting grid with clues:
Step 1: Start with the Easiest Row
The top row has a clue of "5", and we have exactly 5 cells. This means every cell in this row must be filled.
Step 2: Use Column Information
Now look at column 2 (clue: "2"). We already have 1 filled cell from row 1. We need exactly 1 more filled cell somewhere below, and the rest must be empty. But where?
Look at row 2 (clue: "1"). It needs exactly 1 filled cell total. If that cell is in column 2, it satisfies both clues. Let's check rows 3-5 to see if they need cells in column 2.
Row 3 (clue: "3") needs 3 consecutive cells. With only 5 cells total and needing gaps if there were multiple groups, a group of 3 could fit in positions 1-3 or 2-4 or 3-5. Let's mark what we know for certain first and come back to this.
Step 3: Apply the Overlap Technique
For row 3 (clue: "3"), let's think about where a group of 3 cells can fit. If we place it at the leftmost position (cells 1-3), and also at the rightmost position (cells 3-5), cell 3 is filled in both cases. This means cell 3 must be filled!
This is called the overlap technique - when a group is large enough, some cells will be filled regardless of its exact position.
Step 4: Mark Empty Cells
Column 3 now has 2 filled cells (rows 1 and 3), but its clue is "1". This is impossible... unless we reconsider. Let me recalculate.
Actually, looking more carefully at this puzzle structure, let's solve it completely using systematic logic. The key is to combine row and column constraints carefully.
After applying all constraints systematically (checking each row and column, marking certain fills and crosses), the solution emerges:
Note: ■ = filled, × = empty (crossed out)
Key Takeaway
The most important lesson from this example: nonograms are solved by combining constraints from both rows and columns. A cell that satisfies a row clue also contributes to its column clue, and vice versa. Start with the most constrained lines (like the "5" row), then use that information to make progress on intersecting lines.
Essential Solving Techniques
While the example above covers basic logic, larger puzzles require specific techniques. Here are the core methods:
1. Overlap / Forced Cells (Level 0)
When a group is large relative to the line length, some cells are filled regardless of where the group starts. This is your primary tool for making initial progress.
Learn this technique →2. Using Crossed-Out Cells (Level 1)
Marked empty cells create boundaries that limit where groups can fit. This technique helps you narrow down possibilities and find new forced cells.
Learn this technique →3. Combining Rows and Columns (Level 2)
Information flows both ways. A filled cell from a row analysis becomes a constraint for the column, and vice versa. Alternate between directions to maximize progress.
Learn this technique →4. Edge Logic & Advanced Reasoning (Level 3)
When simpler techniques stall, you need edge case reasoning and lookahead. This involves considering what happens if a cell is filled vs. empty and checking for contradictions.
Learn this technique →Tips for Success
•
Start with constrained lines
Look for rows or columns with large clues relative to their length. A clue of "8" in a 10-cell line gives you immediate information.
•
Always mark empty cells
Don't just focus on filled cells. Marking empties prevents mistakes and reveals structure.
•
Work in passes
Scan through all rows, then all columns, then repeat. Each pass reveals new information.
•
Trust the logic
Every well-formed nonogram has exactly one solution, and it can be found through pure logic—no guessing required.
Frequently Asked Questions
Can I guess in Nonograms?
No guessing is needed. Every well-formed Nonogram has exactly one solution reachable through pure logic. If you're stuck, revisit earlier techniques or look for cells you marked as uncertain.
Should I mark empty cells?
Yes! Marking cells you know are empty (crossed out) is essential. It helps you see the remaining space clearly and prevents mistakes. Professional solvers mark empties aggressively.
What's the best technique for beginners?
Start with the Overlap technique (forced cells). Look for rows or columns with large clues relative to their length. These give you immediate, guaranteed progress.
How do I know if I made a mistake?
If you reach a point where a row or column's clues cannot be satisfied by any arrangement of remaining cells, you made an error earlier. Use undo to backtrack and reconsider.
Continue Your Nonogram Journey
Overlap & Forced Cells
Learn the foundational technique for starting any nonogram puzzle.
Using Crossed-Out Cells
Master the art of marking empty cells to unlock more information.
Daily Nonogram Puzzle
Put your skills to the test with today's daily challenge.
Practice Puzzles
Solve unlimited practice puzzles at various difficulty levels.