Nonogram Puzzles
Numbers beside every row and column tell you the runs of shaded cells hidden in it. Work out which cells must be filled and which must be blank, and a picture appears. Every puzzle here is checked first: one solution, and never a guess needed.
Also known as paint by numbers, griddlers, hanjie and picross.
Related Practice
What Is A Nonogram?
A nonogram is a grid with numbers down the side and along the top. Those numbers describe the runs of shaded cells in each line: a clue reading 4 3 means a block of four shaded cells, then at least one blank, then a block of three — in that order, though you are not told where.
Your job is to work out which cells must be shaded and which must be blank. Do it correctly and a picture appears. The puzzle has many names — paint by numbers, griddlers, hanjie — and the video game version has a trademarked one this site does not use.
The Overlap Method
This is the technique the whole puzzle runs on, and it is worth understanding rather than memorising.
Take a line of seven cells with a single clue of five. The run could start at the first, second or third cell — but slide it to the far left and it covers cells 1 to 5; slide it to the far right and it covers 3 to 7. Cells 3, 4 and 5 are covered either way, so they are certainly shaded, without knowing where the run actually sits.
| Run length | Cells forced | Why |
|---|---|---|
| 10 | 10 | It fills the line; there is nowhere to slide. |
| 8 | 6 | Two positions of slack, so the middle six overlap. |
| 6 | 2 | Four of slack, leaving a two-cell overlap. |
| 5 | 0 | Exactly half the line — the two extremes just fail to overlap. |
| 3 | 0 | Far too much slack. Nothing is forced until other cells are known. |
That table explains the difficulty rating on this page, and it is the opposite of what most people expect. A densely filled nonogram is easier, because its runs are long enough to force cells immediately. A sparse one, full of short runs, forces almost nothing early and is much harder work.
Cross Out The Blanks
Marking a cell as definitely empty is a real deduction and skipping it is the commonest reason people stall. A blank splits a line into shorter segments, and a run that no longer fits in a segment has to be somewhere else — which is often the very next thing you need.
That is why this board has three states rather than two. One tap shades a cell, a second marks it as ruled out, a third clears it, exactly as you would with a pencil and a cross.
Line Logic Alone Will Finish Every Puzzle Here
Every picture passes two machine checks before it reaches you.
| Guarantee | How it is checked | If it fails |
|---|---|---|
| Exactly one solution | A search counts solutions and stops at two. | Discarded; a different picture is generated. |
| No guessing required | A solver restricted to line logic must finish it unaided. | Discarded, never shown. |
This matters more for nonograms than for most puzzles, because a randomly drawn picture very often produces clues with two valid readings. Those are thrown away rather than shipped.
That same line solver is what Show me the next move replays: it names one line, says what its clue forces and why, and marks only those cells. Then it stops. A solve button shows you the picture; this shows you how to find it.
Nonogram Puzzles Frequently Asked Questions
What is a nonogram?
A logic puzzle played on a grid where numbers beside each row and column describe the runs of consecutive shaded cells in it. A clue of "4 3" means a run of four shaded cells, then at least one blank, then a run of three. Work out which cells must be shaded and which must be blank and a picture emerges. It is also called paint by numbers, griddlers, hanjie or picross.
What does the overlap method mean?
It is the core nonogram technique. A run of five in a line of seven can start at cell one, two or three — but wherever it starts it covers cells three, four and five, so those three are certainly shaded. The longer the run relative to the line, the bigger the overlap. Runs shorter than half the line give no overlap at all, which is why sparse puzzles are harder.
Should a nonogram ever need guessing?
A well-made one should not, and none here do. Before a puzzle is shown, a solver that only uses line logic — the same overlap reasoning a person applies — must finish it unaided, and a separate search must confirm there is exactly one solution. A picture failing either check is discarded and a different one generated.
Why is marking empty cells so important?
Because a blank cell carries as much information as a shaded one. Knowing a cell is empty splits a line into shorter segments, and a run that no longer fits in a segment must be somewhere else. Solvers who only shade and never cross tend to stall on puzzles that are perfectly solvable, because they keep re-deriving the same partial information.
Are bigger nonograms harder?
Longer, mostly, rather than harder. The technique is identical at 5×5 and 15×15; a large grid just has more lines to revisit before it closes. What genuinely changes difficulty is density — how much of the picture is shaded — because that decides whether the runs are long enough to force cells early.
Why is it called nonogram and not the game name I know?
The best-known name for this puzzle in video games is a Nintendo trademark. Nonogram is the standard generic term and it is what this site uses in the address, the heading and the text. You will also see the same puzzle called paint by numbers, griddlers or hanjie, all of which are free to use.
How do you solve a nonogram?
One line at a time. Take a single row or column, work out every arrangement its clue still allows, and fill in only the cells that all of those arrangements agree on. A run of five in seven cells covers the middle three however it slides, and that overlap is where almost every nonogram opens.
Are nonograms hard to learn?
The rules take a couple of minutes and the main technique takes about twenty. Most people finish their first small grid the same day they read how it works; what takes longer is trusting the crosses, because a puzzle only opens up once you mark what cannot be shaded as carefully as what must be. Larger grids need patience rather than new knowledge.