Nonogram puzzles guide
What Is a Nonogram? Rules, Names and a Short History
Nonograms explained: how the clues work, why the puzzle is also called griddlers, hanjie, picross or paint by numbers, where it came from and how hard it gets.
A nonogram is a logic puzzle played on a grid of empty squares. Each row and each column has a short list of numbers beside it. Those numbers tell you how many squares in that line are filled in, and in what groups. Use the clues to work out exactly which squares to fill, and a hidden picture appears — a cat, a teapot, a sailboat.
There is no arithmetic beyond counting and no guessing in a well-made puzzle. Everything you need is in the clues. Below we cover the rules, the confusing family of names the puzzle goes by, where it came from and what makes one nonogram harder than another.
The rules in one minute
Every nonogram follows the same three rules:
- Each number is a block. A clue of
3means three filled squares in a row, touching each other, somewhere in that line. - Blocks appear in the order listed. A row clue of
2 1means a block of two, then — further right — a block of one. Column clues read from top to bottom. - Blocks are separated by at least one empty square. Two blocks can be separated by one empty square or by many, but they can never touch, otherwise they would count as one longer block.
A clue of 0 (or an empty clue) means the whole line is empty. Everything not covered by a block is empty too. Most solvers mark squares they have proved empty with a small X, so they can see at a glance what is settled.
Here is a tiny solved example. The row clues are on the left, the column clues are stacked above each column, # is a filled square and x is an empty one:
1
3 1 3
3 # # #
1 1 # x #
3 # # #
Row 2 says 1 1: one filled square, a gap, then another. Column 2 says 1 1 too, which is why its middle square is empty. Every line agrees with its clue, so the grid is solved — and the picture is a small square ring.
Griddlers, hanjie, picross: one puzzle, many names
Few puzzles have as many names as this one. They all describe the same rules:
| Name | Where you will see it |
|---|---|
| Nonogram | The most widely used name in English, and the one puzzle researchers use. |
| Griddlers | A popular name on puzzle websites and in some puzzle books. |
| Hanjie | Common in Britain, especially in newspaper puzzle pages. |
| Picross | The name Nintendo uses for its own nonogram video games. |
| Paint by numbers | Used by some puzzle magazines and apps — not to be confused with the hobby kits where you paint numbered areas. |
| Picture cross | A descriptive name used by several mobile games. |
| Japanese crossword | Common in many European countries, a nod to the puzzle's origin. |
If a puzzle gives you a grid, number clues on two sides and asks you to fill squares to reveal a picture, it is a nonogram, whatever the cover says. You will also see names like "logic pictures" and "pixel puzzles" on individual books and apps.
Where nonograms came from
Nonograms were invented in Japan in the late 1980s. Two people are usually credited, working independently: Non Ishida, a graphics editor whose idea grew out of making pictures with the lit and unlit windows of a building, and Tetsuya Nishio, a professional puzzle author. The English name blends Ishida's first name with the word "diagram".
The puzzles reached British readers through newspaper puzzle pages around 1990, which is where names like hanjie took hold, and from there spread to puzzle magazines across Europe. In the mid-1990s Nintendo brought them to handheld consoles with Mario's Picross on the Game Boy, introducing the format to a generation of players. Phones did the rest: a nonogram grid fits a touch screen perfectly, and today they are one of the most popular logic-puzzle genres on mobile.
Researchers have also been interested in them. Solving a nonogram of any size is known to be an NP-complete problem — in general terms, as grids grow there is no known shortcut that solves every possible puzzle quickly. That is part of the appeal for puzzle designers: well-made puzzles are built so that a person can still solve them one logical step at a time.
What solving one actually feels like
You never start by guessing. You start by looking for lines where the clue is so large that some squares must be filled no matter where the block sits. In a row of 10 squares with a clue of 7, the block could start anywhere from square 1 to square 4 — but squares 4 to 7 are covered in every case:
1234567890 leftmost #######... rightmost ...####### certain ...####...
Fill those four, and the columns that cross them now have a starting point. Each new square feeds a crossing line, which gives you another square, and the picture slowly assembles itself. Our step-by-step beginner's guide walks through this overlap method and a complete 5×5 puzzle, and the advanced techniques guide covers what to do when the easy moves run out.
Classic and color nonograms
The original puzzle is black and white: every square is either filled or empty. Color nonograms add a palette. Each clue number is printed in a color, and the blocks must be painted in that color. Color adds one important rule change: two blocks of different colors may touch with no gap between them, while two blocks of the same color still need at least one empty square between them. That small change creates a whole new set of deductions, which we cover in how to solve color nonograms.
Other variants exist — triangular grids, puzzles with clues inside the grid, multi-part mega puzzles stitched from several grids — but classic and color square grids are by far the most common.
What makes a nonogram easy or hard
Grid size matters, but it is not the whole story. A 25×25 puzzle full of long blocks can be quicker than a 15×15 one full of ones and twos. The things that really drive difficulty are:
- Clue length relative to the line. Long blocks create overlap and give you squares immediately. Many short clues give you almost nothing to start with.
- How many clues per line. A line with six small blocks has far more possible arrangements than a line with one.
- How many passes it takes. Easy puzzles fall in one or two sweeps across the rows and columns. Hard ones need you to go back and forth many times, each pass unlocking just a few squares.
- Whether the puzzle is fair. A good puzzle has exactly one solution reachable by logic. A badly made one may have two valid pictures, which forces a guess. Always prefer puzzles that promise a unique, logic-only solution.
Size still changes the experience. A 5×5 puzzle takes a minute; a 25×25 one can take an evening and rewards a methodical approach — see our strategy for big nonograms.
Why people get hooked
- Certainty. Every square you fill is one you proved. There is no luck and no time pressure unless you want it.
- The reveal. Halfway through, a shape you did not expect starts to emerge. Finishing feels like developing a photograph.
- Flexible length. Small grids fit a coffee break; big ones are a long, calm focus session.
- A light brain workout. You hold several constraints in your head at once and check them against each other — the same kind of reasoning sudoku players enjoy, but with a picture at the end.
Where to play nonograms
Newspapers, puzzle books and websites all carry them, and phones are especially well suited to the format. We build NonoPop, a calm nonogram game for Android with classic and color puzzles from 5×5 to 25×25. Every puzzle in it is checked by a solver so it can be finished with logic alone and has one solution, and there is a new Daily Puzzle every day. It can also turn your own photo into a nonogram, processed on your device.
Frequently asked questions
Is a nonogram the same as a picross or a griddler?
Yes. Nonogram, griddlers, hanjie, picross, picture cross and paint by numbers all describe the same puzzle rules. The names differ by country, publisher and brand.
Do nonograms involve math?
Only counting and a little addition. The most useful calculation is adding up a line's clues plus one gap between each pair and comparing that with the line length — it tells you how much room the blocks have to move.
Do you have to guess to solve a nonogram?
Not in a well-made one. Puzzles designed for logic can be completed step by step from the clues. If you find yourself guessing, there is usually a deduction you have not spotted yet.
What does a 0 clue mean?
The whole row or column is empty. Mark every square in it with an X straight away — it is a free head start for every crossing line.