What is a Nonogram?
Nonogram (also called Picross or griddlers) is a picture logic puzzle in which the numbers beside each row and above each column give the lengths of the blocks of filled squares in that line, in order, and you shade the grid until every line matches its clue and a hidden picture appears.
Also known as: Picross, Griddlers, Hanjie, Paint by Numbers.
How do you solve a Nonogram?
- 01
Start with overlap on the longest runs
On a ten-wide line a long run covers the middle wherever it sits. Push it as far left as it can go, then as far right, and fill every square both placements share: a seven fills the centre four squares, a six the centre two. This opens almost every board.
- 02
Settle the lines that leave no choice
A clue of nothing means the whole line is blank, so cross it out. When the clues plus the one blank each pair needs add up to exactly ten, the line has a single arrangement, so fill it.
- 03
Cross out what no run can reach
A gap shorter than the smallest run that still has to go there can never be filled, and squares beyond the reach of the first or last run from the edge are blank too. Crossing out is optional for winning here, but it is how the next deduction becomes visible.
- 04
Grow filled squares toward the edge
If a filled square is within reach of the first clue from the edge and no other run can claim it, that run covers it, and so covers every square between it and the run’s furthest possible start. A filled second square under a first clue of three fills the third and fourth as well.
- 05
Cap a run that has reached its length
When a filled block is already as long as the run it belongs to, the squares at both ends are blank. Cross them, because the crossing lines now know something too.
- 06
Alternate rows and columns, then count
Every square you settle is a fact in two lines, so after a pass down the rows go across the columns and back; a finished line greys its own clue here. Near the end, compare what a line still needs with its unknown squares. Every puzzle on this site has exactly one solution, so a stalled board always has a deduction waiting and a guess is never required.
Common Nonogram mistakes
- Assuming the first clue starts at the edge. A clue of three only says the first run is three long, not where it sits; an edge run is a deduction you have to earn.
- Forgetting the gap between runs. Two runs need at least one blank between them, so four and four on a ten-wide line need nine squares, which is what pins them.
- Never crossing out. Crosses are not needed to win, but an unmarked blank looks identical to an unknown, and the reach-and-gap deductions depend on telling them apart.
- Drawing the picture you think it is. The image is the reward, not a clue, and a square filled on a hunch about the shape poisons every line it touches.
Where does Nonogram come from?
Nonograms were invented twice, independently, in Japan in the late 1980s: by Non Ishida, a graphic designer who came to the idea through pictures made by lighting windows in a tall building, and by the puzzle author Tetsuya Nishio. Ishida’s version reached a British newspaper in 1990 as the Nonogram, a coinage from her surname.
Nintendo made it a household name with Mario’s Picross for the Game Boy in 1995, the start of a series that continues today. Griddlers, Hanjie and Paint by Numbers are the same puzzle under other publishers’ names.
Is Nonogram the same as Picross?
Yes. Picross is Nintendo’s name for the same puzzle, and griddlers, hanjie and paint by numbers are other publishers’ names; the rules are identical.
How long does a 10×10 nonogram take?
Most people finish a ten-by-ten in five to fifteen minutes once overlap is a habit. The daily here is one board of that size, new at midnight UTC, free with no sign-up, and it works on a phone because you paint by dragging.
Can a nonogram have more than one solution?
A carelessly made one can. Every board on this site is checked to have exactly one solution before it is published, so if two arrangements both seem possible, one breaks a clue you have not looked at yet.