How to solve a sliding puzzle

To solve a sliding puzzle, reproduce its tile positions and goal, check whether that goal is reachable, then follow a sequence of slides into the empty space. The online sliding puzzle solver computes that sequence for square boards from 3x3 to 8x8. A slider puzzle, slide puzzle and one-blank sliding tile puzzle use the same rules; the names do not require different tools.

Enter the puzzle you are trying to solve

Choose the same board size as your game. A 3x3 board has eight numbered tiles plus a blank; a 4x4 board has fifteen tiles plus a blank. Use Edit to exchange two tiles until the positions match, or open Type numbers and enter the rows. Read across the top row first, then the next row, ending at the bottom-right. Use 0 or _ for the gap, and spaces, commas or line breaks between numbers.

Every number must occur exactly once. An input with a repeated number or a missing tile is invalid, which is different from a valid but unreachable arrangement. Before solving, compare all rows against your original puzzle. Pressing Shuffle generates another position; it is for trying the tool, not entering the puzzle in front of you.

Check the goal before you search

The default target is ascending numbers with the gap at bottom-right. Some games finish with the gap at top-left or use a different order. Open More → Edit goal to enter that target, then return to the start board. Solvability and the generated moves depend on both arrangements. A correct answer for one target can be wrong for another.

For picture tiles, assign each piece the number of its position in the completed picture, read left to right and top to bottom. Keep that assignment consistent through the whole scramble. The picture puzzle guide explains how to make this correspondence; uploading a scrambled screenshot does not automatically identify its pieces.

A 3x3 solution you can reproduce

This starting board needs two single-tile slides to reach the usual ascending target:

Start                 Goal
1 2 3                 1 2 3
4 0 6                 4 5 6
7 5 8                 7 8 0

1. Slide tile 5 up. It fills the centre blank, leaving the blank at bottom-centre.
2. Slide tile 8 left. It fills that blank, leaving the gap at bottom-right.

The move sequence is 5 ↑, 8 ←. The arrows describe the tiles, not the blank. Both moves are legal because the moving tile is immediately beside the gap. Neither a diagonal move nor exchanging two nonadjacent tiles is a sliding move.

Load this exact 3x3 example, press Solve, and compare its move list with the two steps above. The link sets the arrangement; it does not start a search until you press Solve. The 3x3 solver explanation describes how the example's distance was checked.

Read and follow the solution

Reveal First slide when you want one hint, Opening for the first three moves, or use Solve for the complete sequence. The result gives the next tile, a direction and a progress position. Start playback to watch the sequence, pause when you need to catch up on your own puzzle, or move forward and backward one step at a time. Clicking a move jumps the virtual board to that point; it does not move your physical puzzle for you.

Use Copy moves to save the displayed sequence. Count moves as single-tile slides. If one gesture slides several tiles, each tile still contributes one move. A move count describes the current displayed path; on a 4x4 board a background search may continue after a fast answer is available. See the result labels before comparing answers.

If there is no solution

First check for transcription mistakes, an incorrectly positioned blank or a mismatched goal. If the entries are correct and the tool reports an impossible state, more searching will not create a sliding path. Fix it changes the virtual puzzle by exchanging a pair of tiles. To follow a repaired answer on a physical puzzle, that physical board would need the same change; a repair is not a move sequence for the unchanged original.

Read why some sliding puzzles are unsolvable for a worked parity check. For the classic numbered board, continue with how to solve a 15 puzzle. For larger boards, the 5x5 solver explains the row-and-column reduction used by the tool.