How to Play Picross: Nonogram Solving Techniques

Picross (also called Nonograms or Hanjie) dates to 1987 in Japan, where Non Ishida and Tetsuya Nishio came up with the idea independently; the Picross name was later popularized by Nintendo’s games. See the Nonogram entry on Wikipedia for the full history. The rules: a grid where each row and column has numbers indicating filled-cell run-lengths. Use logical deduction to figure out which cells are filled. Here are the 5 techniques that take you from ‘I can’t even start’ to consistently solving Expert puzzles.

Short answer on how to play Picross: read each row’s and column’s numbers as blocks of filled cells in order, fill the cells that every possible arrangement agrees on, cross out cells that can’t be filled, and keep switching between rows and columns until the hidden picture appears.

Key takeaways

A clue like 3 2 means a block of three, at least one gap, then a block of two, in that order.
Start with the longest clues: the overlap method fills cells before any real deduction.
Crossing out empty cells is as important as filling: crosses create new deductions.
Work rows and columns alternately; each new mark unlocks the crossing line.

Reading the clues

Numbers on a row mean: ‘consecutive runs of filled cells, in order.’ Example: 3 2 means three filled cells, at least one empty, then two filled cells. The minimum length needed is 3 + 1 + 2 = 6 cells.

Same for columns. Together, row and column clues fully determine the picture in a well-formed puzzle (one with a single solution).

A clue of 0 means the line is completely empty: cross out every cell in it straight away. And when a clue’s minimum length equals the grid width, the line is fully determined. In a 5-wide row, 5 fills everything, 2 2 is filled-filled-empty-filled-filled, and 1 1 1 is filled-empty-filled-empty-filled.

Technique 1: Edge solving

Look for rows where one long run takes up more than half the grid width. Then some cells in the middle MUST be filled: every possible placement of the run covers them.

Example: a 10-cell row with clue ‘8’. The 8-cell run must include cells 1-8 OR cells 2-9 OR cells 3-10. The cells that appear in ALL three placements are 3, 4, 5, 6, 7, 8 — the middle 6 cells. Fill them.

Technique 2: Overlap method

For a single run of length R in a row of width W where R > W/2, the overlap is R – (W – R) = 2R – W cells. With several runs, work out the slack first: slack = W minus (the sum of the runs plus one gap between each pair). Any run longer than the slack gets (run length – slack) cells filled in the middle of its range.

Apply to each clue independently. Combine the overlaps. On many puzzles this alone fills a useful share of the grid before you do any ‘real’ deduction.

Row width	Clue	Slack	Cells you can fill at once
5	4	1	Cells 2-4
5	3	2	Cell 3
5	3 1	0	The whole line: cells 1-3 and 5
10	8	2	Cells 3-8
10	4 3	2	Cells 3-4 and 8

Technique 3: X-ing impossible cells

Once you’ve placed some filled cells, look for cells that CAN’T be filled. Mark them with an X (crossed out).

Example: if you’ve established that the first filled cell in row 5 is at column 3, then column 1 and 2 of row 5 must be empty. Mark them with X.

Two more sources of X’s. When a line’s clues are all satisfied, cross out every remaining cell in it. And when you have a completed block that matches the longest clue in its line, cap both ends with an X, because the block can’t grow any further.

Technique 4: Counting from edges

In a 10-wide row with clue ‘4 3’, the LATEST the first run could end is at column 6 (leaving room for 1 empty + 3 filled in columns 7-10). The EARLIEST it could end is at column 4 (cells 1-4).

So the 4-run covers columns 3 and 4 in every placement: fill them. The same counting puts the 3-run somewhere in columns 6-10, which means column 8 is always filled too. The slack here is 2, so this matches the overlap rule above.

This kind of forward-counting from edges narrows down each run’s possible positions.

Gluing to the edge

A filled cell touching the edge of the grid is a gift. If the first cell of a row is filled and the row’s first clue is 3, that block must occupy cells 1-3, and cell 4 must be an X. The same works from the right-hand edge with the last clue, and from an X you’ve already placed, which acts like a wall.

Technique 5: Contradiction (advanced)

If you’re stuck and a cell could be filled OR empty, try one. Follow the deduction chain. If you reach a contradiction (some clue can’t be satisfied), the cell must be the other value.

Solvers often call this trial and error or proof by contradiction. Use it sparingly; well-designed Easy and Medium puzzles solve without it.

A worked start on a 5×5 puzzle

Suppose a 5×5 puzzle has row clues 5, 1 1, 3, 1, 0. Here is how the first moves go:

Row 1 (clue 5): fill all five cells.
Row 5 (clue 0): cross out all five cells.
Row 3 (clue 3): slack is 2, so cell 3 is filled whatever happens.
Now switch to columns. Every column now has a filled cell at the top and an X at the bottom, and column 3 also has a filled cell in row 3. Compare each column clue with what’s there, fill or cross what it forces, then return to the rows.

That back-and-forth is the whole game. Every mark in a row is new information for the columns it crosses, and the other way round.

Common beginner mistakes

Guessing too early. If you haven’t checked every row and column since your last mark, there’s almost always a safe move left.
Skipping the X’s. Crosses are information. A row full of crosses often tells you exactly where its blocks must go.
Forgetting clue order. In 1 3, the single cell comes before the three-block, not after.
Losing count on big grids. Use the thicker lines every five cells as rulers instead of counting from the edge each time.

Practice

Play our Picross at 5×5 (Easy) until you can solve in 2 minutes. Then 10×10. Then 15×15. Bigger grids lean harder on edge counting and cross-checking rows against columns. Our puzzles are randomly generated, and each new puzzle is checked so that it can be solved from the row and column clues alone, so you should never need to guess. If you do fill a wrong cell, it is marked as a mistake and crossed out, so you learn the answer right away. For a different kind of break, the Chrome Dino game needs no logic at all.

The controls are simple. Switch between Fill and Cross mode with the buttons or the F and X keys, or right-click a cell to cross it. Click a filled cell again to clear it. A row’s clue turns green once the row matches, the timer and mistake counter track each attempt, and your best time for each grid size is saved in your browser. A puzzle is solved as soon as every filled cell is in place, so you don’t need to cross out the rest.

Once the basics are automatic, our guide to mastering Picross and nonograms covers harder patterns. If you like this kind of pure deduction, Sudoku and Minesweeper scratch the same itch, and our list of browser logic games has more.

Frequently asked questions

What do the numbers mean in Picross?

Each number is the length of a block of filled cells in that row or column, listed in order. Blocks are separated by at least one empty cell. A 0 means the line has no filled cells.

Is Picross the same as a nonogram?

Yes. Picross, nonograms, Hanjie, Griddlers and paint-by-numbers puzzles are all names for the same kind of puzzle. Picross is the name Nintendo made popular.

Where should you start a Picross puzzle?

Start with the biggest clues and any 0 lines. Big clues give overlap cells straight away, and a 0 line is entirely crossed out. Then look for rows or columns whose clues add up to nearly the full width.

Do you ever have to guess in Picross?

Not in a well-made puzzle. Puzzles with a single solution that can be found line by line never require a guess. On hard puzzles, testing a cell and following it to a contradiction is a logical move, not a guess.

How long does a Picross puzzle take?

It depends on the grid size and your experience. A 5×5 grid is a quick warm-up, while 15×15 grids take noticeably longer because each line has many more possible arrangements.

How to Play Picross — 5 Techniques From Easy to Expert