Nonograms for Beginners: The Rules and a 5x5 Puzzle Step by Step

A nonogram is a grid with a hidden picture: the numbers beside each row and above each column tell you the lengths of the blocks of filled squares in that line, in order, with at least one empty square between blocks. As a beginner, start with the lines you can finish from the clue alone: a 0, a number as long as the line, or numbers that add up to the whole line once you count one gap between each. Then work across: every square you fill or cross out is a new clue for the line that crosses it.

Below, the rules come first, then one complete 5×5 puzzle solved from a blank grid to the finished picture in 7 steps, one row or column at a time. Every diagram on this page is checked by a solver when the site is built, so none of them can show a square that isn't forced. The numbers come from 1,000 puzzles of each size made by Poozee's Nonograms.

The rules in plain words

• The clues are block lengths. A row clue of 3 1 means a block of three filled squares, then a block of one, reading left to right. Column clues read top to bottom.
• Blocks stay in order. The 3 comes before the 1. You never get to swap them.
• At least one gap between blocks. Two blocks always have one or more empty squares between them, or they'd be a single bigger block. Before the first block and after the last one, there can be any number of empty squares, or none.
• A 0 means an empty line. Nothing in that row or column is filled.
• Mark empty squares with an X. An X is just a note that a square is empty. It isn't part of the picture, but it tells you, and the line that crosses it, where blocks can't go.
• One solution. A well-made nonogram has exactly one picture that fits every clue, and you can reach it without guessing. Every puzzle in our game is checked for this before you see it.

The catch is that a clue rarely tells you where its blocks sit. A row of 5 with the clue 2 1 has three possible arrangements:

That's why you work on rows and columns together. A row says "one of these three", a column rules some of them out, and the square that's the same in every arrangement left is the one you can mark.

A first puzzle: a 5×5 solved line by line

Here's the puzzle. Try it on paper first if you like: draw a 5×5 grid, copy the clues, and come back when you're stuck.

In each step below, the tinted row or column is the one we use, blue squares are the ones it just filled and red Xs the ones it just crossed out.

Step 1: row 1 is 2 2

Add up the blocks and one gap between them: 2 + 1 + 2 = 5. That's exactly the width of the row, so there's no room to slide anything. The row has to be two filled, one empty, two filled.

Step 2: row 2 is 5

A 5 in a row of 5 fills the whole row.

Step 3: column 1 is 3 1

Same trick as step 1, on a column: 3 + 1 + 1 = 5, so the column is three filled, one empty, one filled, from the top. The top two squares were already filled, which is a good sign that everything agrees.

Step 4: column 5 is 3 1 too

The right edge has the same clue, so it gets the same pattern.

Those four are the only lines on this grid that you can finish from the clue alone. Together they settled 16 of the 25 squares. From here on, each step uses squares that earlier steps marked.

Step 5: row 3 is 1 1, and both 1s are already there

Row 3 needs a 1 and another 1, and the two ringed squares at its ends are filled. That's both blocks, so the three squares between them must be empty.

Pro tip: Whenever a line has all its blocks, cross out everything else in it at once. A blank square tells the crossing line nothing, while an X tells it exactly where its blocks can't go.

Step 6: row 4 is 3, with only three squares left

Both ends of row 4 are crossed out, which leaves exactly three open squares in the middle. The 3 has nowhere else to go.

Step 7: row 5 is 1 1, and both 1s are there too

Just like row 3, both 1s are already at the ends, so the middle three squares are empty. Those were the last open squares on the grid.

Now check your work: columns 2, 3 and 4 were never used, but they should match their clues. Column 2 reads two filled, one empty, one filled, one empty: 2 1. Column 3 is empty, filled, empty, filled, empty: 1 1. Column 4 matches column 2. Without the Xs, here's the picture:

A complete search confirms the frog is the only picture that fits these clues. Every new 5×5 in our game is a fresh random picture, so you won't meet this exact frog there, but every one of them can be solved with the same routine.

Where to start on any nonogram

The frog started with lines that give away everything at once. Look for them first on every puzzle, in this order:

1. Clues of 0. Cross out the whole line.
2. A clue as long as the line: a 5 on a 5×5, a 10 on a 10×10. Fill the whole line.
3. Clues that add up to the line. Add the numbers, plus one for each gap between them. If the total equals the width, the line fits only one way, like the 2 2 and the 3 1 in the frog. On a 5×5 there are only four such clues besides 5 itself: 1 1 1, 2 2, 1 3 and 3 1.
4. Big numbers. A single block longer than half the line covers the middle squares wherever it slides. On a 5×5, a 4 always covers the middle three squares and a 3 always covers the middle one:

5. Lines that cross what you've marked. After the first few lines, go back over every row and column that gained a filled square or an X, and ask the same question each time: has this line got all its blocks, or is there only one place left for one of them?

The first three rules find what we'll call free lines: lines you can finish from the clue alone, on a blank grid. The third rule matters more than it looks. Of 1,000 5×5 puzzles from our game, 951 had at least one free line, with 2.9 free lines per puzzle on average. Clues that add up to the line were the most common kind: 881 puzzles had one, against 527 with a full line and 84 with a 0. The free lines alone settled 48.3% of all the squares before any other reasoning.

How we measured

We made 1,000 puzzles of each size with the game's own generator (seeds 1 to 1,000), then solved each one a line at a time, the way this guide does: always take the row or column that settles the most new squares, mark everything that line proves, and repeat until the picture is done. Each of those is one step. Every puzzle the game deals can be finished this way, because it keeps only pictures that line-by-line logic solves completely.

At 7 steps, the frog was a little quicker than the average 5×5.

Moving up to 10×10

When 5×5s feel easy, try the Daily puzzle, which is always a 10×10, or the 10×10 button for unlimited ones. Three things change:

• Fewer free lines. Most 10×10s still have at least one, but together they cover only 17.1% of the grid, against 48.3% on a 5×5. On 18.1% of 10×10s there are none at all, and you have to start from the big numbers.
• Big numbers become the main tool. On a 10×10, a single block covers the middle only if it's longer than 5. Our guide to how to solve nonograms explains this "overlap" in detail, with a quick way to count it for clues with several blocks, along with the other techniques bigger grids need.
• You come back to lines. A 5×5 was finished without returning to any line 58.4% of the time. On a 10×10 that dropped to 8.4%, and the 20 lines took 24.3 steps on average, because some lines give up only a few squares at first and the rest once their crossing lines fill in. Keep re-reading any line that just gained a filled square or an X.

When 10×10s feel easy too, our guide to solving big nonograms covers what changes on a 15×15.

Pro tip: If you get stuck in the game, press Hint. It settles one square and names the row or column that proves it and the technique it takes, so you learn where to look next instead of just getting the answer.

Keep playing

• Play Nonograms: a daily 10×10 plus unlimited 5×5, 10×10 and 15×15 puzzles, each solvable by logic alone
• How to solve nonograms: the next step, with overlap, edge forcing, joining and sliding blocks on worked examples
• How to make a nonogram: draw your own frog, then check it has exactly one solution
• How to solve Sudoku for beginners, another logic puzzle walked through from the first move to the last