Slitherlink is a loop puzzle. You join the dots with horizontal and vertical segments to draw one closed loop, so that every numbered cell has exactly that many of its four sides on the loop. Cells without a number can have any number of sides used.

Is this Slitherlink generator free?

Yes. Pick a difficulty, generate a puzzle and print it with its answer, with no sign-up and no watermark. It is free for classroom, home and personal use.

Does every puzzle have one solution?

Yes, and that is the hard part of this genre. A board can satisfy every number and still be drawn as two separate rings, which is not a solution. Every puzzle here is built so its answer is a single closed loop, then checked by the same solver our Publisher Studio uses, so the numbers fix exactly one loop.

Does it include the answer?

Yes. Every puzzle prints as two pages: the puzzle on page one and the finished loop on page two, so you can check your work.

What size are the pages?

The free tool prints at 8.25 by 11 inches, a popular large-print size. Our Publisher Studio will export the same book at any KDP trim, from 5.06 by 7.81 up to 8.27 by 11.69, as a print-ready 300 DPI interior.

Free tool

Free Slitherlink generator, with the answer

Pick a size and generate a Slitherlink, then print it with its answer. Every puzzle has exactly one loop, with no sign-up and no watermark. It runs on the same engine as our KDP Publisher Studio.

Difficulty

Bigger boards with fewer numbers are harder. Every puzzle has one loop.

6×6 board. Join the dots into one closed loop so each number has exactly that many of its four sides on it.

Two pages: the puzzle and its answer. Every puzzle is proved to have exactly one loop by the same engine as our KDP studio.

Want the whole book?

This makes one puzzle. Sign up to turn it into a full Slitherlink book for Amazon KDP: hundreds of graded puzzles at any trim, as print-ready PDFs.

Build the full book

Free to build · pay once to export

Preview

The puzzle and its answer, as they print.

Slitherlink Medium

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Slitherlink Medium · Solution

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How to make a Slitherlink puzzle

1Pick a difficulty. Choose a board. Harder grades are bigger and carry fewer numbers, so more of the loop has to be worked out rather than read off.
2Generate the puzzle. Press Generate puzzle. You get a fresh board, proved to have exactly one loop.
3Print the two pages. Press Print / save PDF. You get two pages: the puzzle on page one and its answer on page two.

How to solve a slitherlink

Join the dots into one closed loop so every numbered cell has exactly that many of its four sides on the loop. Unnumbered cells can use any number of sides.

The method

1Start with the 0s and the 3s. A 0 means none of its four sides are used, so cross all four off. A 3 means three are, which is nearly as strong. Two 3s side by side always share their touching edge.
2Work the corners. A 1 in a corner cannot use either of the two sides on the board edge, so both are out. A 3 in a corner must use both of them.
3Remember every dot has 0 or 2 ends. The loop never stops and never branches, so a dot with one line coming in must have exactly one going out, and a dot with two is finished.
4Refuse the early loop. If closing a line would make a small ring while any other line is still loose, that closure is wrong. There is only one loop in the finished puzzle.

The one rule: One closed loop, no branches, no crossings, and every number counts the sides used around its own cell.
What the answer page shows: The finished loop is printed at the back.
How the grades differ: Harder grades are bigger boards with fewer numbers, so more of the loop comes from the degree rule than from the clues.
Good for: Solvers who like drawing a line more than filling a grid.

Publishing a whole book?

This tool makes one puzzle for home or the classroom. To make a Slitherlink book you can sell on Amazon KDP, Publisher Studio generates hundreds of graded puzzles across a difficulty curve, at any KDP trim, as a print-ready interior and solutions PDF.

See the KDP Slitherlink maker

Questions

What is Slitherlink?: Slitherlink is a loop puzzle. You join the dots with horizontal and vertical segments to draw one closed loop, so that every numbered cell has exactly that many of its four sides on the loop. Cells without a number can have any number of sides used.
Is this Slitherlink generator free?: Yes. Pick a difficulty, generate a puzzle and print it with its answer, with no sign-up and no watermark. It is free for classroom, home and personal use.
Does every puzzle have one solution?: Yes, and that is the hard part of this genre. A board can satisfy every number and still be drawn as two separate rings, which is not a solution. Every puzzle here is built so its answer is a single closed loop, then checked by the same solver our Publisher Studio uses, so the numbers fix exactly one loop.
Does it include the answer?: Yes. Every puzzle prints as two pages: the puzzle on page one and the finished loop on page two, so you can check your work.
What size are the pages?: The free tool prints at 8.25 by 11 inches, a popular large-print size. Our Publisher Studio will export the same book at any KDP trim, from 5.06 by 7.81 up to 8.27 by 11.69, as a print-ready 300 DPI interior.

Short of ideas? Browse our ready-made printables for this puzzle and print one today.