How to Solve Nonograms (Picture Cross): A Complete Guide
Nonograms — also sold as Picross, picture cross, griddlers or hanjie — hide a pixel picture behind number clues. Each number lists the runs of filled cells in a row or column, in order, with at least one gap between runs. That single rule generates surprisingly deep logic, and the best part is that a well-made board never needs a guess. Here's the complete toolkit, from your very first move to the habits that carry you through 15×15 boards. You can practice everything below on our free Nonogram, which generates unlimited boards that are always solvable line by line.
1. Start with the overlap technique
The overlap (or "big number") technique is the engine of every nonogram solve. Take a run and imagine sliding it as far left as it can go, then as far right. Any cells covered in both extremes must be filled in every legal arrangement — so fill them now.
Concretely: a 7-run in a 10-wide row occupies cells 1–7 at the far left and 4–10 at the far right. Cells 4–7 are covered either way — four guaranteed fills from a single clue. The bigger the number relative to the line, the bigger the overlap; a clue equal to the line's length fills it completely. Scan every row and column for these before doing anything else.
2. Work the edges
Whenever a filled cell touches a wall — or an ✕ you've placed — the run it belongs to is anchored. If the edge cell of a row with clue "4 2" is filled, the 4-run occupies exactly cells 1–4, and cell 5 must be empty. Mark that ✕ immediately: anchors are how one deduction becomes three.
3. Mark the ✕s — they're half the game
Beginners fill cells and ignore the empties. Experts know a proven-empty cell is worth just as much: every ✕ splits a line into smaller independent segments, and short segments are easy. If a segment between two ✕s is shorter than the next run that must fit there, the whole segment is empty — ✕ it out. When a line's runs are all placed, ✕ every remaining cell; those ✕s become anchors for all the crossing lines.
4. Count what's left
Mid-solve, re-read each clue against what's on the line. A row clued "1 3" that already shows a filled single and a filled triple is done — close it with ✕s. A row clued "5" with three adjacent fills can extend at most two cells in either direction; anything further out is ✕. This "what could this line still be?" re-scan is where most stuck players find their next move.
5. Alternate directions in passes
Nonograms are solved in waves: a pass over the rows creates new information in the columns, which creates new information back in the rows. If you stall, don't stare harder at one line — sweep the other direction. On our boards this loop is guaranteed to finish the puzzle: the generator verifies every board completes through line logic alone, with a unique solution (that's the same no-guess standard behind all Funduk logic games).
6. When you're stuck, use hints that teach
Our Nonogram has a hint system built for learning: the first press highlights the line whose clue forces a move and explains the deduction in plain words; a second press plays it for you. It's the fastest way to internalize overlap thinking — see the reasoning a few times and you'll start spotting it yourself.
Common mistakes to avoid
- Guessing. If a fill "feels right", it isn't logic. There is always a forced move somewhere — usually in the direction you haven't swept recently.
- Forgetting the gap rule. "2 2" is never four in a row; runs need at least one empty cell between them.
- Reading clues out of order. The first number is the first run you meet reading left-to-right (or top-to-bottom). Order matters.
- Fill-only play. If you never place ✕s, 10×10 and larger boards will stall. Empties are information.
Where to play
Play unlimited free nonograms — 5×5 to 15×15, plus a shared Daily Challenge with streaks — on Funduk Nonogram. No login, no download, and every board is guaranteed solvable by pure logic. If you like line-by-line deduction, try our SunMoon (binary balance) and no-guess Minesweeper next.