How to Solve Nonograms: 7 Techniques From First Line to Last

A nonogram is a grid with numbers along the top and the side. Fill the right squares and a picture appears. Learning how to solve nonograms comes down to a handful of techniques you use over and over, one line at a time. None of them needs a guess.

You can try every technique below in Nonograms on HulaGames, free in your browser. The first picture is a guided 5×5 that shows you each move, and every puzzle after it, from 5×5 to 15×15, is solved by logic alone.

1. Read the clues the right way

Each number is a run of filled squares in that row or column, in order from left to right or top to bottom. Runs in the same line have at least one empty square between them. A row marked “2 3” has a run of 2, a gap, then a run of 3. A row marked “0”, or with no number, is all empty.

2. Fill the lines that fit exactly

Add up the runs in a line, plus one empty square between each pair. If the total equals the width, there’s only one way to place them. In a 10-wide row, “4 5” is 4 + 1 + 5 = 10, so the row is fully known: four filled, one empty, five filled. A single 10 fills the whole row.

3. Use the overlap rule

Most lines don’t fit exactly, but they often come close. The spare room is the width minus the runs and their gaps. In a 10-wide row with one run of 7, the spare room is 3. Slide the 7 as far left as it can go, then as far right: the middle 4 squares are filled either way. Fill them.

The rule works with several runs too. Any run longer than the spare room gets that many squares filled, minus the spare. In a 10-wide row with “3 4”, the runs and gap take 8 squares and the spare room is 2, so the 3 gets 1 sure square and the 4 gets 2.

4. Mark the squares that stay empty

Empty squares are clues as well. When a line’s runs are all placed, mark every other square in it with ✕. When a run is complete, the squares on each side of it are empty. Those marks matter, because they shrink the room left for the crossing lines.

5. Work in from the edges

A filled square near the edge pushes the first run along. If a row’s first run is 4 and its second square is filled, the run must cover squares 2 to 4. It can’t start any later, because then it would miss the filled square. The same works from the right with the last run, and from the top and bottom in columns.

6. Mark squares no run can reach

Look for gaps between ✕ marks or the wall that are too small for any run left in the line. If a column’s runs are all 3 or longer, a gap of 2 between two ✕ marks must stay empty. Squares beyond the reach of the last run, once it’s pinned, are empty too.

7. Go back and forth, and never guess

Every square you fill or mark gives the crossing line new information. A good rhythm is to finish what one line tells you, then check every line that crosses the squares you just changed. When you’re stuck, look for the line with the biggest numbers or the fewest unknown squares left.

You never need to guess in a well-made puzzle. On HulaGames, if you’re stuck, Hint shows a square you can work out next, and Mark ✕ lets you keep track of every empty square as you go.

Practice on three sizes

Nonograms on HulaGames has 5×5 puzzles to learn on, 10×10s for a coffee break and 15×15s for a longer think. Every picture you solve joins your Island album, with 69 library pictures to find, and today’s Daily is one 15×15 that’s the same for everyone.

Like logic puzzles? Our guide to logic puzzles for beginners covers more puzzle types to try, and building a daily puzzle habit shows how to fit one into five minutes a day.