The Complete Beginner's Guide to Nonograms

1. What a nonogram is (and the one rule)

A nonogram— also called picross, griddler, or hanjie — is a grid of empty squares with numbers running along the top and down the left side. Your job is to fill in some of the squares and leave the rest blank. When you get it right, the filled squares form a small picture: a cat, a key, a sailboat, whatever the puzzle hides.

Here is the entire rule, the only one you ever need to remember: the numbers on each line tell you the lengths of the filled runs in that line, in order, with at least one empty square between runs. That's it. Everything else in this guide is just clever ways of using that one rule.

The beautiful part: a well-made nonogram never requires guessing. Every square can be worked out by pure logic from the clues you already have. If you ever feel like you have to guess, you've simply missed a deduction somewhere — the answer is always there to be found.

2. How to read the number clues

Each row has its clues on the left, read left-to-right. Each column has its clues on top, read top-to-bottom. A clue of 3 means “somewhere in this line there are exactly 3 filled squares in a row.” A clue of 2 1 means “a run of 2, then a gap of at least one empty square, then a run of 1” — in that order. The order of the numbers always matches the order of the runs along the line.

Let's make that concrete with a tiny 5×5 puzzle. Below, the numbers around the grid are the clues, a filled square is shown as █ and a known-empty square as ·. Here is the solved grid so you can see what we're aiming for:

         1
     5 1 3 1 5
   +-----------
 5 | █ █ █ █ █
1 1| █ · · · █
 3 | · █ █ █ ·
1 1| █ · · · █
 5 | █ █ █ █ █

Now imagine that grid empty and let's deduce a few squares from scratch:

• ✓Row 1 has the clue 5. The row is only 5 wide, so a run of 5 fills it completely — every square in the top row is filled. No thinking about position needed: it can only fit one way.
• ✓Row 5 is also clue 5, so the bottom row fills completely too. Two whole rows solved already.
• ✓Column 1 (leftmost) has the clue 5 as well — five filled squares in a column that's only 5 tall — so the entire left edge is filled. The same is true of column 5 on the right edge.

With four edges and two rows placed, the rest falls out quickly: the middle row's clue of 3 must sit in the centre, and the 1 1 rows just keep their two edge squares and stay empty in between. That little frame-with-a-bar picture is your first solve. The key insight: clues that equal the line length can be filled instantly, and those filled squares immediately constrain the lines that cross them.

3. The first four moves to make on any puzzle

When a fresh grid appears, don't try to read it all at once. Run through these four moves in order and you'll almost always crack it open:

1. 1
   Fill any full lines

   Scan for clues that equal the line length (like the 5s above), or a single clue that's one or two short of full. A clue of 8 in a 10-wide grid can't avoid the middle squares no matter how you slide it — those centre cells are guaranteed filled. This is the overlap idea, and it's the fastest way to put the first real marks on the board.

2. 2
   Use overlap on the big clues

   For any large clue, picture sliding its run as far left as it can go, then as far right. Any square that's covered in both extremes must be filled. You don't need to know exactly where the run sits — you only need the squares that can't be avoided. Big clues overlap themselves the most, so start there.

3. 3
   Mark the empties with an X

   Every time you finish a run or rule out a square, mark it empty (an X or dot) right away. A blank square is ambiguous — it could still be anything. An X is a decision, and decisions are what let you place the next run with confidence.

4. 4
   Work the most-constrained lines first

   After your first fills, hunt for the lines with the least wiggle room: long clues, many clues crammed into a short line, or lines that already have a few squares decided. Those are where the next forced moves hide. Whenever you fill or empty a square, glance at the crossing line — that's where most fresh deductions come from.

That loop — fill the forced squares, mark the empties, move to the next tightest line — is the whole game. When you want sharper tools (edge logic, gap counting, forcing), the advanced solving techniques page goes deeper.

4. Marking empties is half the game

New players obsess over which squares to fill and ignore the empty ones. That's a mistake. In a nonogram, knowing a square cannotbe filled is exactly as valuable as knowing one must be — sometimes more. Every X you place removes a possible position for a run, which often forces that run into the one spot left for it.

A simple example: suppose a 5-wide row has the clue 3 and, from a crossing column, you've already learned the first square is empty. Mark it with an X. Now the run of 3 can only fit in the last four squares — and with a single X you've learned that the middle squares are forced. Without that X, you'd be staring at the same row seeing nothing.

So mark empties relentlessly. The board fills with information even when you're not filling squares, and that information is what unlocks the next move. A grid covered in confident X's solves itself far faster than a grid of nervous blanks. If a term ever trips you up — run, gap, overlap — the glossary defines them all.

5. When a line is done, you're done with it

The moment a line's runs all match its clue, that line is finished — and every remaining square in it is empty. Fill those X's in immediately. People leave completed lines half-marked and then waste time re-reading them; a finished line should be visibly, unambiguously done.

On this site, the clue numbers for a satisfied line turn a different colour, so you get a built-in checkmark: once a line's numbers light up, you can stop thinking about it and spend your attention on the lines that are still open. It's a small bit of feedback that keeps you honest and quietly confirms you're on the right track.

Closing out lines as you go is also how you catch mistakes early. If a finished line forces a contradiction in a crossing line, you'll see it right away instead of three moves later. Validate as you go, trust the logic, and the picture will appear — one solved line at a time.