Logic Puzzles
Slitherlink Puzzle
Draw a single closed loop along grid lines using number clues.
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What this tool does
Slitherlink puzzles on an 8x8 dot lattice. Draw a single closed loop along grid edges so every numbered cell has exactly that many of its four sides on the loop. Two puzzles per page.
Settings
Configure your Slitherlink
2 8x8 slitherlink per PDF.
Size
Paper size
Preview
Sample puzzle (mini)
Dotted lattice with number clues — draw a single closed loop along the lines.
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Create Printable Slitherlink Puzzles — Draw a Single Closed Loop Using Number Clues
Quickly create free printable Slitherlink puzzles, also known as loop-the-loop or Fences. Draw one single closed loop along the grid lines so every numbered cell has exactly that many of its four sides on the loop.
Generate Slitherlink puzzles in A4 or US Letter PDF format for puzzle clubs, long flights, quiet evenings, and deduction practice. Choose the grid size, decide how many puzzles per page, and optionally include the full solution key.
Slitherlink is one of the most elegant of all loop puzzles. A tiny rule set produces surprisingly deep deduction, and every move you make shapes the single continuous loop that gives the puzzle its name.
Why use this Slitherlink generator?
Slitherlink does not appear in many puzzle books outside Japan, which makes a self-generated supply especially useful. Use it for:
- puzzle club meetings
- travel puzzles for seasoned solvers
- classroom enrichment on deduction and proof
- quiet evenings away from screens
- tutor sessions on careful reasoning
Two puzzles per page gives plenty of working room for dots, partial edges, and crossings-out.
What you can customise
- Grid size: the default 8x8 dot lattice offers a comfortable challenge
- Puzzle count: two puzzles per page by default
- Solutions page: add or omit a second page with the full loop drawn in
- Paper size: download as A4 or US Letter PDF
- Seed: reproduce an identical puzzle set later
The dot lattice is rendered large enough that you can trace loop segments in pen or pencil without worrying about accuracy.
Notes and limitations
- Every puzzle has exactly one single, non-branching, closed loop.
- Cells marked 0 have no loop edges; cells marked 3 have exactly three.
- In v1 the engine generates puzzles from random "blob" regions, so strict uniqueness verification is not yet enforced.
- Print at 100% scale so the dot lattice prints crisply.
Who Slitherlink is for
Beginners
Slitherlink has a gentle on-ramp. Start with small grids (6x6 or 8x8), focus on 0 and 3 clues — they dictate obvious moves — and grow confident with one rule at a time.
Puzzle enthusiasts
Experienced solvers love Slitherlink for the "aha" moments when a chain of deductions closes off an entire region. Two 8x8 puzzles make a pleasing twenty-minute sitting.
Classroom teachers
Slitherlink teaches proof-style thinking: every move should be justified by the clues around it. Use the sheet as an enrichment activity or as a talking point for deductive reasoning lessons.
Parents
Parents use Slitherlink as a quiet activity for older children, a train-journey puzzle, or a shared evening challenge.
How Slitherlink works
The grid is a lattice of dots. You draw short line segments between neighbouring dots to form a single closed loop that never crosses itself and never branches.
- A 0 means none of the four surrounding edges is on the loop.
- A 1, 2, or 3 means that many edges are on the loop.
- No number means you have no direct constraint at that cell.
How to use the tool
- Choose the grid size.
- Pick the number of puzzles per page.
- Turn the solutions page on or off.
- Select your paper size: A4 or US Letter.
- Click Generate.
- Preview the sheet.
- Download the PDF.
Worked example
For a first-time solver, generate two 8x8 puzzles with solutions on. Tell them to start with every 0 and 3 clue: 0s block all four edges, while 3s force three of four edges on. Those moves alone usually kick off a long chain of deductions.
For a puzzle club, generate two 8x8 puzzles with solutions off on US Letter. Solvers can sign their sheets when they finish and swap to compare loops.
Methodology
The generator selects a contiguous region of cells, treats its boundary as the target loop, and derives the clue number for each cell by counting how many of its edges lie on the boundary. Random thinning removes some clues to create a pleasing density. The optional solution page redraws the grid with the loop traced in.
Helpful preset ideas
- Two 8x8 puzzles per page for a classic sitting
- Solutions off for a clean travel puzzle
- Solutions on for teacher-friendly marking
- Seed values for repeatable club sheets
Tips for solving Slitherlink
- Always start with 0s and 3s — they force the most edges at once.
- Use little X marks on edges you can prove are not part of the loop.
- Check corners carefully: a 1 in a corner has only two possible loop edges.
- Remember the loop must eventually close — isolated loop fragments are a sign of an error.
Designed for A4 and US Letter Printing
The Slitherlink worksheet is tuned for both A4 and US Letter. Dot spacing and clue text size are calibrated for both paper sizes, so the puzzle feels consistent whichever printer you use.
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You may also enjoy these related printable logic puzzles:
FAQs
Quick answers
How do the numbers work?
Each numbered cell tells you exactly how many of its four sides are part of the loop (0, 1, 2 or 3).
Where does the loop start?
The loop is closed and has no special start — every cell is either inside or outside it.
Are puzzles guaranteed unique?
In v1 the puzzles are derived from a random "blob" of cells; uniqueness is not strictly verified.
Want a similar challenge?
Try Masyu — also a single-loop puzzle but with circles instead of numbers.
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