The fastest way to get better at Nonograms is to do the certain work first: sweep every line for overlaps before you think, fill the lines whose clues fill them, and after each move look straight at the lines that cross it. We measured these tips on 100 of the game’s puzzles at each size, and the numbers below come from those tests.
These build on how to solve Nonograms. If you haven’t played before, start with the rules.
Solving tips
1. Sweep for overlaps before anything else
Go through every row and column on the empty grid and fill the overlaps. It feels slow, but it’s the biggest single step of the puzzle:
| Size | Share of the picture from the opening sweep |
|---|---|
| 5×5 | 80% |
| 10×10 | 63% |
| 15×15 | 49% |
On a 10×10, that’s nearly two thirds of the filled squares before you’ve had to work anything out. The slack rule tells you which lines to look at: any block longer than the line’s slack has an overlap.
2. Find the lines that fill themselves
When a clue’s numbers plus one gap between each add up to exactly the line’s length, there’s only one way to fill it. A 10-square row with 4 1 3 (4 + 1 + 1 + 1 + 3 = 10) is completely settled: blocks and gaps both. On the game’s puzzles there are about 1.8 of these per 5×5, 1.3 per 10×10 and 0.9 per 15×15, so check for them first.
3. Work back and forth
Every square you settle changes two lines: the one you were working on, and the one crossing it. Look at the crossing lines next. After a move, one of the lines crossing the squares you just changed has a quick move waiting 83% of the time on a 5×5, 80% on a 10×10 and 68% on a 15×15. Searching the whole grid is only worth it when that runs dry.
4. Cross out as you go
When a line is finished, cross out the rest of it straight away. When a square can’t be filled, cross it. A crossed-out square is what lets the crossing line pack its blocks tighter, and every technique except finished lines uses crosses.
5. Close off the biggest block
If a run of filled squares is as long as the biggest number in the clue, that block is complete: no block is bigger. The squares on both sides of it must be empty.
None of the five quick techniques spots those two crosses on the row above; only listing every arrangement would. And it’s always right: we checked it against the full line solver on 5,000 random part-filled lines.
6. Count in fives
The grid has a darker line every five squares. Use it to count: on a 15-square row, “two past the second thick line” is square 12, without counting one by one.
Tips for playing on PeerPuzzles
7. Drag to fill a whole run
Press on a square and drag along the row or column to fill (or cross out) a run in one go. A drag only changes squares that started like the first one, so dragging across a mix of filled and empty squares never wipes out work you’ve already done. Undo (or Ctrl/Cmd + Z) takes back a whole drag at once.
8. Cross out without switching modes
On a computer, right-click to cross out a square. On a phone, switch to Cross. On a keyboard, X switches between Fill and Cross.
9. Let the clues tell you when a line is done
A clue turns grey when its line matches it. The row and column under your pointer are highlighted, so you always know which two clues a square answers to. And if you’re stuck, Stuck? (or H) names a line and the technique to try on it, without giving the squares away.