Nonogram Solver
Enter the clues, then follow the solution one row or column at a time. The solver also tells you whether the clues need a guess, or fit more than one picture.
Enter the numbers of each line in order, separated by spaces, commas or dots. Write 0 for an empty line.
How to enter a nonogram
- Choose the number of columns and rows, from 2 to 30 each.
- Type the clue of every row, top to bottom, and of every column, left to right: the numbers in order, separated by spaces, commas or dots. Write 0 for a line without filled cells. On a phone the number keyboard opens, and its dot or comma key separates numbers. To move to the next field, use Next on Android or the arrow above the keyboard on an iPhone. On a computer, Enter moves on.
- Press Solve. Clues that cannot be right, such as 5 5 in a line of 10 cells, are listed with the line they belong to, and nothing is solved until they are corrected.
- Or load one of the examples: practice nonogram 1 of this site, a small grid that needs a guess, and one with two solutions.
The rows and columns must ask for the same number of filled cells in total. If they do not, a clue was mistyped, and the solver says so before it starts.
Reading the steps
The grid starts blank. Next step shows the next row or column that decides at least one cell: its clue is underlined, the cells it decides are framed, and the text names them. Cells are counted from the left in a row and from the top in a column, so "Row 3, clue 8. Filled: 3–8." means that the third row fills its cells 3 to 8.
Previous step goes back, and Last step jumps to where line logic ends. Large cells makes a big grid easier to read on a phone; it then scrolls sideways inside its frame.
What the result means
| Result | What it tells you |
|---|---|
| Solved by line logic | Exactly one picture fits, and it can be found one row or column at a time, without guessing. |
| Exactly one solution, line logic not enough | Only one picture fits, but single lines stop deciding cells before the end. A person needs to reason across several lines at once, or try a cell and see what follows. |
| More than one solution | At least two pictures fit the clues. The two shown differ in the framed cells. A puzzle meant for solving should be changed. |
| Search gave up | The search reached 20,000 tries before deciding. The steps of line logic are still correct; the clues may have no solution, one or several. |
| No solution | No picture fits every clue; usually a clue was entered wrongly. |
For someone who makes nonograms this is the useful part: when the first result appears, the puzzle can be solved by hand one line at a time, without guessing.
How the solver works
Line logic takes one row or column at a time. It lists every way to place the runs of the clue that agrees with the cells already decided. A cell that is filled in every way is filled; a cell that is empty in every way is crossed. The solver goes through the rows, then the columns, and again, until a whole pass decides nothing new. It is the same reasoning that the daily nonograms of this site are checked with.
When line logic stops before the grid is full, a search takes over: it tries a cell as filled and as empty, applies line logic after each try, and keeps going until it has found two solutions or has shown that there are fewer. This tells one solution from several, but it is not shown as steps, because it is not how a person solves.
Limits
- Only line logic is explained step by step. Reasoning that combines several lines, which some hard puzzles need, is not.
- The search gives up after 20,000 tries. On a large grid with very little line logic it can say that it does not know whether the clues have no solution, one or several. The steps of line logic are still correct. Such a search can take a minute on a phone.
- Grids from 2 × 2 to 30 × 30 cells, black and white only. Colour nonograms, and reading clues from a photo, are not supported.
Example: practice nonogram 1
Load Example: practice nonogram and press Solve. The result is solved by line logic in 31 steps.
Step 1 is row 2 with the clue 6. A run of 6 cells in a row of 10 can start anywhere from cell 1 to cell 5, and cells 5 and 6 are covered in every case, so they are filled. Step 2 is row 3 with the clue 8: every placement covers cells 3 to 8. Row 1, clue 2, is not a step: a run of 2 can sit anywhere in 10 cells, so it decides nothing. The solver goes through the rows from the top, then the columns from the left, and the columns use what the rows decided.
Frequently asked questions
- Can the solver solve any nonogram?
- It finds the picture of any black and white nonogram up to 30 × 30 that has one, unless the search reaches its limit. It explains the steps only as far as line logic goes.
- Can a nonogram have more than one solution?
- Yes. The smallest case is two filled cells on a diagonal of a 2 × 2 square: the clues are the same for either diagonal. The solver shows two solutions and frames the cells where they differ.
- How do I know whether my puzzle needs guessing?
- Enter it and press Solve. If the result is solved by line logic, it can be solved one line at a time; otherwise the solver says how many cells line logic decides before it stops.
- Does the solver send my clues anywhere?
- No. It runs in your browser; the clues you enter are not sent or stored.
Last updated: September 29, 2026