Strategy
Nonogram Solving Tips & Strategy
A practical solving guide for nonograms: work the most constrained line first, force overlaps with the 2L − N rule, carry every fill into the crossing line, cross out proven blanks, and never guess.
Play NonogramsThe core idea
Always work the tightest line available
Every strong nonogram habit comes down to one principle: spend your attention on the line that has the least freedom right now, extract everything it forces, carry that into the crossing lines, and repeat. Solving is never a search — if you feel the urge to guess, there is a deduction you have missed.
- 01
Attack the most constrained line first
Do not read the grid top to bottom. Scan for the line — row or column — whose clue leaves the least freedom, and act there. A clue whose length is close to the line length forces squares before you have done any cross-referencing at all.
- 02
Use the overlap formula
For a single run of length L in a line of length N, the centre 2L − N squares are filled in every valid position. Push the run hard left, then hard right; anything filled both times is filled now. This is the fastest way to open a blank grid.
- 03
Carry every fill into the crossing line
The value of filling a square is rarely in its own line — it is in the line that crosses it. After each fill, look at that column (or row) and re-evaluate its clue with the new information before you continue.
- 04
Count the mandatory gaps
A clue of "2 3 1" needs 2 + 1 + 3 + 1 + 1 = 8 squares minimum. Knowing that number tells you the slack in the line, and the slack tells you which runs have forced squares.
- 05
Cross out blanks as you prove them
An empty square and a proven-blank square look identical, and that hides deductions. Mark blanks immediately: a line with its blanks crossed often reveals that a run can only sit one way.
- 06
Anchor runs against edges and blanks
If the first square of a line is filled and the first clue is a run, that run starts at the edge — place all of it and cross the square after it. A blank square anywhere in a line acts as an edge for the runs on either side.
- 07
Finish a line the moment its total is met
When the filled squares in a line add up to the sum of its clues, every remaining square in that line is blank. Cross them all and move your attention elsewhere.
- 08
Never guess
Every puzzle here is verified solvable by logic. A position that feels like a coin flip means there is a deduction you have not found, almost always in a line that crosses the one you are staring at. Step back and rescan rather than filling on a hunch.
By phase
How the approach shifts as the grid fills
The techniques are the same throughout — see the techniques section of the guide — but which one is most useful changes.
Opening
Apply the overlap formula to every long clue on the board. Anchor any run whose edge square is already filled. You should have a scattering of filled and crossed squares in most lines before you do any real cross-referencing.
Middle
Alternate rows and columns relentlessly. Each newly filled square tightens a crossing clue; each crossed square removes a possibility. This phase is where a disciplined crossing-out habit pays for itself.
Endgame
Near the finish most lines are nearly full. Use line totals to blank out the rest, and let the satisfied-clue dimming tell you which lines are done so you stop re-reading them.
Ready to put it into practice? Read the full how-to-play guide or jump straight in.
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