Slitherlink Solver, Step by Step
Tap a square to put in its number: once for 0, again for 1, 2, 3, and once more to clear it.
How to use the slitherlink solver
Set the width and height to match your puzzle, then tap each numbered square until it shows its number. Press Explain the next step: the solver draws the next lines that are certain, or crosses out edges that cannot be part of the loop, highlights the number or dot that proves it, and says why. Show the answer draws the whole loop and checks it is the only one.
The rules of slitherlink
Draw a single closed loop along the lines of the grid, going from dot to dot. Each number says how many of its square's four sides the loop uses; squares without a number can have any. The loop never crosses itself or branches, so every dot has either no line or exactly two.
How to solve slitherlink, step by step
Start with the 0s and 3s. A 0 crosses out all four of its sides at once. Count each number's sides. When a number has all its lines, its other sides are crossed out; when it has exactly as many sides left as it still needs, they are all lines. Never stop at a dot. A line that reaches a dot has to leave it, so if only one way out is left, it goes that way, and a dot with only one possible edge has no line at all. No small loops. Joining a line to itself closes a loop, which is only allowed when it is the whole answer. Those moves solve every daily puzzle on this site; for harder ones the solver tries an edge both ways and keeps the one that does not break a rule.
How it was checked
The solver was run on all 150 puzzles of the daily slitherlink. It drew each stored loop, found it to be the only one, and explained every puzzle from the first line to the last without drawing or crossing a single edge wrongly.
More loop and path puzzles
There is a new daily slitherlink every day. The Zip puzzle solver draws one path through every square, and the nonogram solver explains its steps the same way. For a puzzle you hold in your hands, see our brain teasers. There are more solvers on the puzzle tools page.
Frequently Asked Questions
How do you solve slitherlink?
Start with the 0s, which cross out all four sides, and the 3s. Count each number's sides: when it has all its lines, cross out the rest; when it has exactly as many sides left as it needs, they are all lines. A line can never stop at a dot, and the loop can never close early on itself.
What are the rules of slitherlink?
Draw one closed loop along the grid lines, dot to dot, so that each number shows how many of its square's four sides the loop uses. The loop never crosses itself or branches.
What does a 0 mean in slitherlink?
That none of the square's four sides is part of the loop, so all four can be crossed out straight away.
Is slitherlink the same as Loop the Loop or Fences?
Yes, slitherlink is sold under several names, including Loop the Loop, Fences and Loopy. The rules are the same.
Does every slitherlink have one solution?
A well-made one does. The solver checks, and says if the numbers you entered allow more than one loop.