Rubik's Cube & puzzles
How to solve nonograms: the rules and five strategies that always work
Learn how to solve nonograms, also called Picross or Griddlers: what the number clues mean, the overlap trick, crossing out, edges and gaps, with free nonogram puzzles to practise from 5×5 to big grids.
A nonogram is a grid puzzle where number clues tell you which squares to fill. Solve it and a picture appears. They are also called Picross, Griddlers, Hanjie or Paint by Numbers, and a well-made one never needs guessing.
The rules
Each row and column has a clue like 3 1. That means: in this line there is a block of 3 filled squares, then at least one empty square, then a block of 1, in that order. A clue of 0 means the line is empty.
Five strategies
1. Fill the overlap
In a row of 10, a block of 7 must cover the middle squares wherever it sits: slide it fully left and fully right, and the squares covered both times (here, squares 4 to 7) must be filled. Big numbers give big overlaps, so start with them.
2. Cross out what's done
When the filled squares in a line already match its clue, every other square in that line is empty. Mark them with a cross so you don't fill them by mistake.
3. Use the edges
A filled square touching the edge must belong to the first (or last) block, so you know where that block starts. Fill the rest of the block and cross the square after it.
4. Count the space
If the clues plus their gaps exactly fill a line (for example 2 3 4 in a row of 11: 2 + 1 + 3 + 1 + 4 = 11), the whole line is decided.
5. Switch direction often
Every square you fill in a row gives information to a column. Work back and forth between rows and columns, and the puzzle opens up.
Practise for free
Our free nonogram puzzles have 24 pictures in three tiers: 5×5 starters, 10×10 pictures and big grids. Clues fade when a line is complete, hints show which line proves the next square, and every puzzle is checked by a solver to have one answer you can reach by logic alone. When you finish, the tiles flip over to reveal a colourful pixel picture.
Common questions
Do you ever have to guess in a nonogram?
Not in a good one. A well-designed nonogram has exactly one solution that logic can reach. All the puzzles in our game are checked to make sure.
What is the difference between nonograms and Sudoku?
Both are logic puzzles with one solution. Sudoku places numbers so that each appears once; nonograms decide which squares are filled, using clues about block lengths, and reveal a picture.
Are nonograms good for kids?
Yes. Small 5×5 nonograms suit children from about 8 and build careful reasoning and concentration.
This guide is general information. For exams, follow your school, teacher and official exam board, and use your own judgement about what suits your child.