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Nonogram Solver, from clues to picture.

Use this free nonogram solver to turn row and column clues into the finished picture. Enter any grid up to 25×25, press Solve, and replay the line-by-line logic step by step to see exactly how each cell was decided. It also tells you when a puzzle has more than one answer or none at all.

How it worksLine logic

Interactive

Nonogram Solver

Grid size10×10

Rows

10

Columns

10

Type each clue as numbers separated by spaces, like 3 1. A blank box or a 0 means an empty line. Pasting several lines fills the boxes in order, and Enter jumps to the next box.

Row clues (top to bottom)
Column clues (left to right)

Type the clues for each row and column to begin (a blank box counts as an empty line).

Nonogram grid, 10 rows by 10 columns, 0 cells filled so far.

The clues you type appear around the grid. Press Example to see a finished puzzle first.

Field guide

How the Nonogram Solver works.

A nonogram is a picture puzzle drawn on a grid. Each row and each column carries a short list of numbers, and your job is to decide which cells to fill so that every list is satisfied at once. The same puzzle is sold under several names, including Picross, Griddlers and Hanjie. The rules never change: the answer is a black-and-white picture, and good puzzles have exactly one.

Reading the clues

Every number is a block of consecutive filled cells. A row clue of 3 1 means a block of three, then at least one empty cell, then a block of one, in that order from left to right. Column clues read from top to bottom. A clue of 0, or no clue at all, means the whole line is empty. Because blocks need gaps, a line can never be shorter than this:

minimum length = sum of blocks + (number of blocks − 1)

The solver checks this for you. If a clue cannot fit in its row or column, the box turns red and the message names the line.

Entering your puzzle

Set the number of rows and columns first, then type one clue per box, separating the numbers with spaces. Pressing Enter moves to the next box, and pasting several lines at once fills the boxes in order, which is the quickest way to copy a long list. The clues you type are drawn around the grid as you go, so you can compare the screen with your puzzle before you solve. The Example button loads a small original picture, written for this tool, if you want to watch a full solve first.

What the solver is doing

First it works on one line at a time. For a given row it considers every way the clue could be laid out given the cells already known, and keeps only what is true in all of them. If a cell is filled in every possible layout, it is filled; if it is empty in every layout, it is empty. Each row and column is revisited whenever a crossing line changes, until nothing new appears. The step slider replays exactly this process, highlighting the line being solved and the cells it decided.

Most published puzzles fall completely to this logic. When a few cells stay undecided, the solver tries each one both ways and follows the consequences. A guess that breaks a clue proves the opposite value. If that still is not enough, it searches depth first, and it keeps going after the first answer to check for a second. A limit on the work done means a hopeless input ends with a message instead of freezing the page.

Worked example

Take a row of 10 cells with the clue 6 2. The blocks and the gap need 6 + 1 + 2 = 9 cells, so there is exactly one cell of slack. The block of six can start in cell 1 or cell 2, which means cells 2 to 6 are filled either way. The block of two can occupy cells 8–9 or 9–10, so cell 9 is filled too. Without knowing anything else, six cells of that row are already settled. Every block longer than the slack leaves some cells fixed in this way, and it is the first thing to look for by hand.

When there are several answers, or none

The row clues and the column clues must add up to the same total, since each filled cell is counted once in a row and once in a column. If they do not, the solver says so before it starts. If the totals agree but no picture fits, the message points to the line where the logic clashed. If several pictures fit, one is shown and the cells that differ in a second valid picture are outlined. Published puzzles are built to have one answer, so either message usually means a digit was misread.

Tips for solving nonograms yourself

  • Start with the big numbers. A clue that nearly fills its line leaves very little slack, so many cells are forced straight away.
  • Mark the empty cells too. Crossing out cells that can never be filled shortens the space the remaining blocks can use.
  • Work from the edges. A filled cell touching the border starts the first block there, which settles that block completely.

Disclaimer: This tool is an independent fan creation and is not affiliated with, authorized, or endorsed by Nintendo Co., Ltd. “Picross”, “Griddlers” and similar names are trademarks of their respective owners and are used here only to describe the type of puzzle. Provided for practice and entertainment only.