Nonogram Solver
Type the row and column clues of any picross, griddler or hanjie puzzle and watch it solve itself, one deduction at a time.
Every solver on the web will print you a grid. This one shows the reasoning: which row or column gave way, which rule applied to it, and which cells that rule settled. Play it back one step at a time and the next puzzle will not need a solver at all.
Enter the clues
Everything runs in your browser. No clues are uploaded and no account is needed.
The answer
How to Use the Solver
- Set the grid size. Width and height are independent, so non-square puzzles work; anything from 2×2 up to 25×25 is supported.
- Type each row's clue into its own field, with spaces or commas between the blocks — 3 1 2. Leave a field empty when the row has nothing filled in.
- Do the same for the columns. Watch the two totals underneath: they count the same filled cells from two directions, so they have to agree before a solution can exist.
- Press Solve. Everything runs in your own browser, and the answer comes back with an honest verdict — one solution, several, none, or too big to decide.
- Switch to Step by step to replay the solve one deduction at a time and see which technique broke each line open. Download the grid as a PNG or copy the link to share the puzzle.
How Nonogram Clues Work
A nonogram clue is the list of block lengths in that line, in the order they appear. A row clue of 3 1 2 means a run of three filled cells, then at least one blank, then a single filled cell, then at least one blank, then a run of two. The clue never says where the blocks sit — only how long they are and what order they come in.
That is why the shortest possible layout matters so much. Add up the blocks, then add one blank between each neighbouring pair: 3 1 2 needs 3 + 1 + 1 + 1 + 2 = 8 cells at minimum. If the line is only 8 wide there is exactly one way to lay it out. If it is 10 wide the blocks have two cells of slack to slide around in, and the overlap between the leftmost and rightmost layouts is what you can fill in straight away.
Every filled cell is counted once by a row clue and once by a column clue, so the two sets of totals must come to the same number. The solver adds them up as you type: if they disagree, a clue has been mistyped and no grid can satisfy both.
The Techniques the Solver Uses
Every deduction the solver makes is one of these seven, and the step-by-step view names the one it used each time. They are worth learning: between them they finish almost every published puzzle without a single guess.
- Line overlap
- Push the blocks as far towards one end as they will go, then as far towards the other. Any cell filled in both extremes is filled in the answer, whatever it turns out to be. A clue of 8 in a 10-wide line overlaps on 6 cells before anything at all is known.
- Forced line
- The blocks plus one blank between each neighbouring pair add up to exactly the length of the line, so there is only one way to lay them out. The whole line is settled in a single move.
- Edge forcing
- A filled cell hard against the end of a line must belong to the block nearest that end, which pins where the block starts. The rest of the block follows at once, and the cell just past it is blank.
- Completed runs
- As soon as a line holds as many filled cells as its clue asks for, every cell still undecided in that line has to be blank. Cheap, and it is what turns one solved row into progress on ten columns.
- Gap elimination
- A stretch of undecided cells shut in between blanks, shorter than the smallest block still waiting to be placed, cannot hold anything. Every cell in it is blank.
- Empty line
- A clue with no numbers means nothing in that line is filled. Marking it costs nothing and it often unlocks every line that crosses it.
- Candidate elimination
- The general case, and the one everything above is a shortcut for: list every way the clue could sit in the line, throw out the layouts that clash with cells already known, and fill in whatever the survivors all agree on.
Logically Solvable Versus Guessing
Line logic is what a person actually does: look at one row or one column, work out everything that clue forces given the cells already known, mark those cells, move on. Nothing else. A puzzle is logically solvable when repeating that is enough to fill the whole grid, and every well-made nonogram is built to be exactly that — there is always some line that can be pushed a little further.
A puzzle that is not logically solvable stops the process dead: no line yields anything, and the grid is still full of holes. Sometimes that is because the clues genuinely allow more than one picture. The smallest example is a 2×2 with the clue 1 on both rows and both columns — one filled cell per row and per column, which either diagonal satisfies. Nothing distinguishes them, so no amount of reasoning can pick one.
Other times the answer is unique but hidden behind a guess: you have to assume a cell, follow the consequences, and back out if they contradict. This solver does that search for you and reports which case you are in — but it also keeps a budget, and when the budget runs out it says so rather than calling the puzzle unsolvable. Giving up looking is not the same as proving there is nothing to find.
Frequently Asked Questions
What is a nonogram?
A nonogram is a picture logic puzzle. Numbers along the top and down the side tell you the lengths of the filled blocks in each column and row, and working out where those blocks can go reveals a picture. The same puzzle is sold as picross, griddler, hanjie, paint by numbers and crucipixel — the rules are identical, so this solver handles all of them.
Is a picross solver the same as a nonogram solver?
Yes. Picross is Nintendo's name for the puzzle, griddler and hanjie are the names used by British and Japanese publishers, and nonogram is the neutral term. None of them changes the rules, so any picross, griddler or hanjie grid can be typed straight into the fields above.
Why does the solver say my puzzle has no solution?
Almost always a mistyped clue. Check the two totals under the fields first — every filled cell is counted by both a row clue and a column clue, so if the sums differ, at least one number is wrong. If the totals match, look for a line whose blocks and gaps add up to more cells than the line has; the solver flags those in red as you type.
What does it mean when a puzzle needs guessing?
It means line-by-line logic ran out of deductions before the grid was full. A well-made puzzle never does this: it is designed so that some line can always be advanced. When it happens, the puzzle either has more than one valid answer, or it has exactly one that can only be found by trying a cell and seeing whether the rest falls apart. The solver tells you which of the two it is.
Are my clues uploaded anywhere?
No. The solver is JavaScript running in your own browser tab, on your own device. Nothing you type is sent to a server, there is no account to make, and closing the tab is all it takes to throw the puzzle away. The share link carries the clues inside the address itself rather than storing them anywhere.
What size puzzles can it solve?
Anything from 2×2 up to 25×25, and the two sides do not have to match — a 20×10 grid is fine. Bigger grids take longer, so the solver works to a time budget and stops rather than freezing the tab. If it runs out of time it says so honestly instead of pretending the puzzle is unsolvable.