How to Solve Your First Nonogram
Decode nonogram clues, find forced overlaps and solve an original five-by-five picture. Learn why marking empty cells is as useful as filling them.
Read the clues in order
A black-and-white nonogram describes runs of filled cells in every row and column. A clue of 3 means one uninterrupted group of three. A clue of 2, 1 means a group of two followed later by a group of one, with at least one empty cell between them. Clue order matters.
The puzzle has three useful cell states: filled, confirmed empty, and unknown. A blank-looking unknown is not the same as a proven empty cell. Conceptis’s publisher rules below are the reference for this black-and-white format. Color nonograms may use different separation rules, so do not transfer this guide blindly to those variants.
Look for exact fits
A five-cell row with clue 5 is completely filled. A five-cell row with clues 2, 2 has only one arrangement: two filled cells, one empty, then two filled. The clue lengths use four cells and the mandatory separating gap uses the fifth. There is no room to slide either group.
For any line, add the group lengths and one separator for each gap between groups. That gives the minimum required length. Comparing it with the line length tells you how much sliding space remains. Do not add a mandatory gap before the first group or after the last: those outside gaps are optional.
Find the cells that overlap
For a seven-cell line with a single clue 5, imagine the run as far left as possible: cells one through five. Now slide it as far right as possible: cells three through seven. Cells three, four and five are filled in both extremes, so they are forced.
Cells one, two, six and seven remain unknown. Filling the overlap does not tell you that the run is centered. It could still start at one, two or three. Keep that distinction clear, then use the intersecting columns to discover which complete placement is possible. Forced cells are information; guessed edges are trouble.
Solve an original five-by-five example
Try this small puzzle on paper. Its row clues from top to bottom are 1 / 1 / 5 / 1 / 1. Its column clues from left to right are also 1 / 1 / 5 / 1 / 1. Begin with row three and column three: each has clue 5, so fill every cell in both.
Now each other row already contains its required single filled cell, at column three. Mark all its other cells empty. The same is true for each other column. The completed picture is a plus sign. Read its rows as [..#..], [..#..], [#####], [..#..] and [..#..]. The deductions specify every cell, so there is no alternative solution.
Close finished runs carefully
If you know a particular run is complete, mark the empty separator immediately before and after it when those cells exist. Those empty cells prevent accidental merging with another run. The new boundaries can force the neighboring runs into smaller spaces.
First confirm which clue the run belongs to. In a row with clues 2, 4, a visible pair might be the whole first run or only part of the second. Automatically surrounding every pair with empty marks would be an error. Use existing boundaries, available length and clue order to identify the run before closing it.
Alternate rows and columns
Work one line until it yields a forced fill or empty cell, then inspect the crossing lines. Every new cell can reduce their placement options. If nothing changes, move to another line instead of repeatedly extending a group by intuition. The hidden picture can be a reward, but should not serve as your proof.
When a contradiction appears, such as two groups touching without a separator, review your last unsupported extension. Keep a short explanation for each move: exact fit, overlap, completed run, or crossing constraint. Once that routine feels natural on small grids, larger pictures become a sequence of manageable line problems.
Sources & further reading
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