Nonogram

How to play a nonogram

The numbers are runs of filled cells, read left to right for rows and top to bottom for columns. Here’s a whole 5×5 puzzle in five moves. Rows count from the top, columns from the left.

1. The middle column says 5, so you fill all of it.
2. The middle row says 1 1 1. Three single cells with a gap between each need all five cells, so they take the first, third and fifth.
3. The left and right columns each say 1, and the middle row just filled it. Cross out the rest of both columns.
4. Row two says 3. Its end cells are crossed out now, so the run takes the middle three.
5. Every line now has its runs. Cross out the empty cells and the arrow is done.

Three beginner techniques

You’ll use these on every puzzle. The guide to solving nonograms has more, plus a 5×5 puzzle solved from an empty grid.

Overlap in long runs

A long run can’t move far. Push it as far left as it goes, then as far right. Any cell it covers both times is filled, wherever the run ends up. A 7 in a row of 10 always covers the middle four.

Start from the edge

The edge of the grid stops a run. If the first cell of a row is filled, it’s the start of the first run. With a clue of 4, that run is the first four cells, and the rest of the row is empty.

Cross out finished lines

Once a line has all its runs, every other cell in it is empty. Cross those cells out. A cross is as useful as a filled cell, because it blocks runs in the line going the other way.

Sizes and difficulty

A new nonogram comes out every day at midnight in your time zone. Difficulty follows the week:

• Monday and Tuesday are easy: a 10×10 picture.
• Wednesday and Thursday are medium: a 15×15 grid.
• Friday to Sunday are hard: a 20×20 grid. There’s no picture to guess at, so you follow the clues all the way. Some rows only give up a cell once you weigh every way their clue fits.

A solver checks every puzzle before it’s published. Each one has a single answer that you can reach one row or column at a time, without guessing. On a phone, pinch to zoom into the bigger grids; the clues stay pinned to the edges while you move around.

Where nonograms come from

Nonograms come from Japan. In 1987 Non Ishida, a graphics editor, won a competition in Tokyo with pictures made from skyscraper windows, some lit and some dark. That gave her the idea for grid puzzles, and in 1988 she published three of them as “Window Art Puzzles”. Tetsuya Nishio, a professional puzzle maker, came up with the same idea on his own and published his in a different magazine.

James Dalgety, a British puzzle collector, named them nonograms: “Non” from Ishida’s name and “gram” from diagram. From 1990 The Sunday Telegraph printed one every week.

The puzzle has picked up other names since: griddlers, hanjie, paint by numbers, picture logic puzzles and Japanese crosswords. Nintendo’s Picross games use the same rules too.

Nonogram questions

What does nonogram mean?

The name joins “Non”, from Non Ishida, one of the two people who invented the puzzle, with “gram” from diagram. A nonogram is a grid where number clues tell you which cells to fill to make a picture.

Are nonograms always solvable?

Not every set of clues makes a fair puzzle. Some fit two different pictures, and some can only be finished with a guess. A solver checks every Owlpuzzles nonogram before it goes out, so each one has one answer you can reach by logic.

Are nonograms good for your brain?

They’re a good daily mental workout: you keep several clues in mind and check every step. There’s no proof that puzzles like these prevent memory loss or dementia, so play them because you enjoy them.

How many 5×5 nonograms are there?

A 5×5 grid can be filled in 33,554,432 ways, since each of its 25 cells is either filled or empty. Fewer make good puzzles, because some grids share their clues with another grid and the clues can’t tell them apart.

How can I create a nonogram puzzle?

Draw a picture on squared paper and count the runs of filled cells in each row and column. Those counts are your clues. Then solve it from the clues alone. If you get stuck or find a second answer, change a few cells and try again.

More puzzles to try

If you like ruling cells out one line at a time, try star battle: place stars so every row, column and region has the same number. Queens puzzle is its smaller one-star version, good for a short break. Shikaku uses number clues too, but you split the grid into rectangles instead of filling cells.

For more techniques and a full worked example, read how to solve a nonogram.