A nonogram hands you an empty grid and a row of numbers next to every row and column. That’s the whole puzzle. Read those numbers correctly and the hidden picture falls out through logic, no guessing required, no trial and error needed to get unstuck.
The single move that separates people who finish nonograms from people who quit halfway through is called the overlap trick, and it’s covered in detail further down. Everything else in this guide, the edge logic, the habit of marking cells with an X, the constant back-and-forth between rows and columns, exists to support that one technique.
You can try every example below on a real board at our free nonogram puzzles, which come in 5×5, 10×10, and 15×15 sizes. No account, no download, and every puzzle on the site is checked by machine before it goes live to confirm it can be solved by pure logic with one unique answer.
What the clues mean
Each clue is a list of numbers giving the length of every filled run in that row or column, in the order the runs appear from left to right (for rows) or top to bottom (for columns). A clue of “3 1” means a block of three filled cells somewhere in the line, followed later by a single filled cell, in that order. There has to be at least one empty cell between them, maybe more, but they can never touch. That gap rule is the part beginners forget: “3 1” can never collapse into a run of four.
A clue with just one number, like “7”, means one continuous run of seven filled cells, with the rest of the line empty. A blank clue, sometimes shown as “0”, means the whole line is empty. Once you can read “2 3 1” and picture three separate runs of two, three, and one, each with a gap before the next, you already understand the notation.
Your first solve step by step
Picture a 5×5 grid meant to draw a plus sign. The row clues, top to bottom, are 1, 1, 5, 1, 1. The column clues, left to right, are 1, 1, 5, 1, 1. That symmetry isn’t a coincidence, it’s what makes this a good first puzzle to walk through in your head.
Start with the biggest clue on the board: the middle column’s “5”. In a grid that’s five cells tall, a run of five has nowhere to go but everywhere, it must fill the entire column top to bottom. That’s edge logic in its simplest form: when a clue equals the full length of the line, the whole line is filled, no calculation needed.
Now look at the top row. Its clue is just “1”, meaning one filled cell and four empty ones, and on its own that clue doesn’t say where. But you already know the middle cell of the top row is filled, because the middle column is filled all the way down. Since the row’s clue allows only one filled cell total, and you’ve already found it, the other four cells in that row must be empty. That’s cross-referencing: a fact proved in a column becomes the missing piece for a row, and back again. Repeat it for the second, fourth, and fifth rows, and the plus sign appears without a single guess.
The overlap trick
Overlap is the technique that unlocks puzzles fastest, and it works before you know anything else about a line. Take a row 10 cells wide with a single clue of “7”. Slide that run as far left as it will go: it lands on cells 1 through 7. Slide it as far right as it will go: it lands on cells 4 through 10. Compare the two. Cells 4, 5, 6, and 7 are filled in both versions, so they’re filled no matter where the run actually sits. Shade those four in immediately, with zero risk.
Cells 1 through 3 and 8 through 10 stay unknown, since the run could start anywhere from position 1 to 4 and those outer cells aren’t filled in every one of those positions. You didn’t need any other information on the board to find the guaranteed middle section. Rule of thumb: whenever a clue is longer than half the line, overlap gives you free cells, and the longer the clue, the more you get. A clue of “9” in that same row would hand you eight guaranteed cells before a single other deduction.
Four habits that speed everything up
- Mark finished lines with an X, not just a mental note. Once a row’s filled cells match its clue, every remaining cell in that row is blank, and marking it stops you from re-scanning the same row three times.
- Work the edges before the middle. Cells at the start or end of a line have fewer possible positions than cells in the center, which is why the plus-sign column above resolved instantly.
- Treat rows and columns as one conversation, not two separate puzzles. Every cell you fill from a row can make its column solvable too, and back again.
- Solve the biggest clues first. A run of 8 in a 10-wide line gives overlap immediately; a run of 1 tells you almost nothing until nearby cells are resolved.
Common mistakes
The biggest one is guessing when a line feels ambiguous. If you can’t prove a cell is filled or empty using clues, other filled cells, or X-marks already on the board, the move isn’t to pick one and see what happens, it’s to switch to a different row or column and come back later with more information. A single wrong guess several moves deep can force you to undo far more work than the guess saved.
Second is forgetting the mandatory gap between runs. If a row reads “2 2” and you’ve found four cells in a row all filled, something is wrong, because those two runs can never touch. Recheck your work rather than assuming the puzzle made an exception.
Third is solving a line in isolation and never coming back to it. Nonograms get easier as the board fills in, because cells you couldn’t place early on often become obvious once neighboring rows or columns are locked down. If a line stalls, leave it and return after you’ve made progress nearby.
If you’d rather warm up on something with fewer moving parts, our sudoku beginner’s guide covers a similar no-guessing approach for number logic instead of picture logic.
Frequently asked questions
Is guessing ever needed to solve a nonogram?
No, not on a properly built puzzle. Every well-formed nonogram has a solution reachable through line logic alone, meaning there’s always at least one guaranteed cell to find if you look hard enough. On our site specifically, every puzzle is machine-checked before publishing to confirm a unique solution exists without guessing.
What’s the difference between nonograms, picross, and griddlers?
They’re the same puzzle under different names. “Nonogram” is the term most common online and in Japan, “picross” comes from Nintendo’s Picture Crossword games and stuck in gaming circles, and “griddlers” is the name used by several newspaper and magazine publishers. The grid, the clues, and the logic are identical across all three.
How long does a nonogram take, by size?
A 5×5 typically takes a couple of minutes once you know the overlap trick, closer to five minutes if you’re still learning. A 10×10 usually runs 10 to 20 minutes. A 15×15 can take 30 minutes or more, mostly because cross-referencing between rows and columns has more lines to track at once.
Are nonograms good for your brain?
They exercise logical deduction, the same kind of step-by-step reasoning you use when ruling out possibilities one at a time. That’s a useful mental habit to practice regularly, though a single puzzle session is a modest workout, not a substitute for anything else.
Once the overlap trick and the row-column habit click, the rest is repetition. Start with a free 5×5 nonogram and work up to the 15×15 boards once the small grids stop giving you trouble. For more logic and picture puzzles to rotate through, our roundup of brain games websites worth bookmarking is a good next stop.
