Nonogram Solving Guide
How to reveal the hidden picture from number clues alone — rules, first moves, mid-game techniques, and printing, all on one page.
What is a nonogram?
A nonogram is a logic puzzle where number clues on each row and column tell you which cells to fill, gradually revealing a hidden picture. Also known as picross, griddlers, or picture logic, it has been a staple of puzzle magazines in Japan and Korea for decades.
This app offers four sizes, from 5×5 up to 20×20, playable right in your browser. Every puzzle is verified to be solvable through line logic alone, all the way to the end — so if you feel stuck, it is never time to guess: there is always a clue you have not found yet.
The rules at a glance
The numbers on a row or column list the lengths of its consecutive filled blocks, in order. "3 1" means a block of three cells, then at least one empty cell, then a single cell, reading from the left (or the top). Blocks are always separated by at least one empty cell.
Mark cells you know are empty with an X. Confirmed-empty cells drive your next deductions just as much as filled ones do — experienced solvers mark X generously.
Making the first moves
Start with the big numbers. When a block is longer than half the line, its leftmost and rightmost possible placements must overlap. In a 10-cell line, an "8" always covers the middle six cells no matter where it sits — so you can fill those six immediately.
A "0" line is all X. A line whose numbers plus mandatory gaps exactly fill its length — like "4 5" in ten cells — is fully determined. Clearing these free lines first scaffolds the whole board.
Mid-game techniques
The heart of nonograms is cross-referencing rows against columns. One filled cell in a row narrows that column's clue, and a confirmed X in a column pins down block positions in its row. When a line stalls, do not stare at it — follow the cells you just changed into their crossing lines.
A block touching the edge extends to its full length at once, with an X sealing its end. Completed clues also get X on both ends of their blocks. Once you settle into the rhythm of fill, propagate X, and re-check crossings, even 15×15 and larger boards shrink steadily.
Choosing size and difficulty
If you are new, learn the rules on 5×5 and move up to 10×10. The 15×15 and 20×20 boards are proper 10-to-30-minute puzzles, with zoom and pan support that keeps them comfortable on mobile.
There are three difficulty tiers: easy, medium, and hard. Harder boards confirm fewer cells per pass, demanding deeper back-and-forth between rows and columns. The curated dot-art puzzles, each with a name and a picture, are a great way to taste the joy of completion first.
Solving on paper
Any puzzle prints on a single A4 sheet. The solution comes on a separate answer page, and scanning the QR on the printout reopens the same puzzle online.
Pencil-and-paper nonograms make great classroom activities and brain training for seniors. Print several copies of the same board, solve together, and compare with the online records.
Getting the most from this app
Every puzzle carries a short code. Note the code and you can reopen the exact same puzzle anytime, or send it by link or QR to race a friend on the same board. Records stay on your device — no account needed.
Every Monday (UTC), a fresh weekly challenge opens across ten size-and-difficulty slots. The whole world gets the same puzzles, so sharpen the techniques in this guide and take on the global leaderboard.