Nonogram
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Nonogram Solving Guide

How to reveal the hidden picture from number clues alone. This page covers the rules, first moves, mid-game techniques, and printing.

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What is a nonogram?

A nonogram is a logic puzzle where number clues on each row and column tell you which cells to fill, and the filled cells gradually reveal a hidden picture. Nonograms, also known as griddlers or picture logic, have been a staple of puzzle magazines in Japan and Korea for decades.

This app has four sizes, from 5×5 up to 20×20, playable in your browser. Every puzzle is verified to be solvable through line logic alone, all the way to the end, so you never need to guess. If you feel stuck, 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 gives you a starting point for the whole board.

Mid-game techniques

The main technique in 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, leave it and 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, you make steady progress even on 15×15 and larger boards.

Solve one 5×5 puzzle, step by step

Try this fixed beginner puzzle before opening the four steps below. The diagrams, playable puzzle, and printout all use the same clues and the same code.

Rows run from R1 at the top to R5 at the bottom; columns run from C1 on the left to C5 on the right. R2C3 means row 2, column 3. The bold numbers beside these labels are the clues.

A blank cell is undecided, a solid cell is filled, and × means confirmed empty. A thick inner border marks a cell newly decided in that step.

Starting puzzle — all 25 cells undecided
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
R2Clue:3UndecidedUndecidedUndecidedUndecidedUndecided
R3Clue:5UndecidedUndecidedUndecidedUndecidedUndecided
R4Clue:3UndecidedUndecidedUndecidedUndecidedUndecided
R5Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
Solve this puzzlePrint this puzzle

Puzzle code: N1.BSO-4gA.b1aea79f

Open one step at a time. Each explanation shows the board before and after its deductions, so you can pause and find the next move yourself.

1. Fill a complete row and find the overlap

R3 has clue 5, so fill all five cells. R2 has clue 3: its block could occupy C1–C3, C2–C4, or C3–C5. Only C3 appears in every placement, so R2C3 must be filled.

R4 also has clue 3, so fill R4C3 by the same reasoning. Seven cells are now filled. Leave the other cells undecided until a clue forces them.

Before step 1
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
R2Clue:3UndecidedUndecidedUndecidedUndecidedUndecided
R3Clue:5UndecidedUndecidedUndecidedUndecidedUndecided
R4Clue:3UndecidedUndecidedUndecidedUndecidedUndecided
R5Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
After step 1
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
R2Clue:3UndecidedUndecidedFilledNewly decided in this stepUndecidedUndecided
R3Clue:5FilledNewly decided in this stepFilledNewly decided in this stepFilledNewly decided in this stepFilledNewly decided in this stepFilledNewly decided in this step
R4Clue:3UndecidedUndecidedFilledNewly decided in this stepUndecidedUndecided
R5Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
2. Cross to a column, then mark completed rows

C3 has clue 5. Its middle three cells are already filled; fill R1C3 and R5C3 to complete the column.

R1 and R5 each have clue 1, now satisfied by their C3 cell. Mark C1, C2, C4, and C5 in both rows with ×. These eight cells are confirmed empty, which will constrain the crossing columns.

Before step 2
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
R2Clue:3UndecidedUndecidedFilledUndecidedUndecided
R3Clue:5FilledFilledFilledFilledFilled
R4Clue:3UndecidedUndecidedFilledUndecidedUndecided
R5Clue:1UndecidedUndecidedUndecidedUndecidedUndecided
After step 2
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1Confirmed emptyNewly decided in this stepConfirmed emptyNewly decided in this stepFilledNewly decided in this stepConfirmed emptyNewly decided in this stepConfirmed emptyNewly decided in this step
R2Clue:3UndecidedUndecidedFilledUndecidedUndecided
R3Clue:5FilledFilledFilledFilledFilled
R4Clue:3UndecidedUndecidedFilledUndecidedUndecided
R5Clue:1Confirmed emptyNewly decided in this stepConfirmed emptyNewly decided in this stepFilledNewly decided in this stepConfirmed emptyNewly decided in this stepConfirmed emptyNewly decided in this step
3. Use the outer columns to confirm four more × marks

C1 has clue 1, and R3C1 is already filled. Every other cell in C1 must be empty. R1C1 and R5C1 already have ×; add × at R2C1 and R4C1.

C5 also has clue 1, already satisfied at R3C5. Add × at R2C5 and R4C5. Rows 2 and 4 now have confirmed-empty cells at both ends.

Before step 3
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
R2Clue:3UndecidedUndecidedFilledUndecidedUndecided
R3Clue:5FilledFilledFilledFilledFilled
R4Clue:3UndecidedUndecidedFilledUndecidedUndecided
R5Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
After step 3
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
R2Clue:3Confirmed emptyNewly decided in this stepUndecidedFilledUndecidedConfirmed emptyNewly decided in this step
R3Clue:5FilledFilledFilledFilledFilled
R4Clue:3Confirmed emptyNewly decided in this stepUndecidedFilledUndecidedConfirmed emptyNewly decided in this step
R5Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
4. Fill the remaining blocks and check every clue

R2 needs a block of 3. With C1 and C5 empty, it can only occupy C2–C4. C3 is already filled, so fill R2C2 and R2C4. Repeat for R4C2 and R4C4.

All 25 cells are decided and a diamond appears. Check the columns from left to right: their filled runs are 1, 3, 5, 3, 1, exactly matching the clues. The rows match too.

Before step 4
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
R2Clue:3Confirmed emptyUndecidedFilledUndecidedConfirmed empty
R3Clue:5FilledFilledFilledFilledFilled
R4Clue:3Confirmed emptyUndecidedFilledUndecidedConfirmed empty
R5Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
After step 4
Row and column cluesC1Clue:1C2Clue:3C3Clue:5C4Clue:3C5Clue:1
R1Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty
R2Clue:3Confirmed emptyFilledNewly decided in this stepFilledFilledNewly decided in this stepConfirmed empty
R3Clue:5FilledFilledFilledFilledFilled
R4Clue:3Confirmed emptyFilledNewly decided in this stepFilledFilledNewly decided in this stepConfirmed empty
R5Clue:1Confirmed emptyConfirmed emptyFilledConfirmed emptyConfirmed empty

Carry each new filled cell or × into its crossing line. In this example, a full row and overlap led to a full column, completed clues gave empty cells, and those empty cells fixed the remaining blocks. The same sequence is useful on larger boards.

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, so you need more back-and-forth between rows and columns. For a first taste of finishing a puzzle, try the curated Picture puzzles, each with its own name and drawing.

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 work well as classroom activities and as 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 has 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, and you do not need an account.

Every Monday (UTC), a fresh weekly challenge opens across ten size-and-difficulty slots. Players worldwide get the same puzzles, so practice the techniques in this guide and compete on the global leaderboard.

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