ROOM FOR A CHECKED RECTANGLE
Shikaku Solver.
Bring a grid. Check its rectangles.
Understand one next step.
YOUR CLUES, ONE STEP AT A TIME
Enter a Shikaku grid
Use . or 0 for an empty square. Enter 2–9 rows and 2–9 columns. The numbers must add up to the grid area.
Applied puzzle
Read board as text
Row 1, column 1: 3. Row 2, column 2: 3. Row 3, column 3: 3.
No steps applied.
Clues and applied steps stay in this browser. Nothing is solved until you ask.
FROM A COPIED CLUE TO A CHECKED STEP
How to use the Shikaku solver
Partition every square into rectangles. Each rectangle contains exactly one clue, whose number is its area.
- Copy the grid. Use a space between squares and a new line between rows. A dot or zero means an empty square. Keep empty squares between distant clues; their positions matter.
- Apply your clues. The tool checks dimensions and numbers before replacing the applied puzzle. Invalid text stays editable. Applying clues clears the previous explained steps.
- Choose your help. Explain next step previews a deduction, and Apply explained step adds it to your working board. Undo reverses steps in this tab. Solve checks all completions within a bounded search and shows a separate answer preview.
READ THE EMPTY SQUARES TOO
A small input example
The two rows below make a 2×2 grid. Each 2 covers two squares. The clues on the left force two horizontal rectangles; putting both clues in the same vertical rectangle would break the one-clue rule.
2 . 2 .
CHECK THE MEANING, NOT JUST THE PICTURE
Before using an answer
What do unique, multiple and no solution mean?
A unique result proves exactly one complete answer fits the applied clues and steps. Multiple means at least two fit; only one is previewed. No solution means none fit. Check copied numbers and positions before assuming the original puzzle is wrong.
Does a limit mean the puzzle is impossible?
No. Each check runs in a background browser worker with a 100,000-node and two-second search budget. A timeout or worker failure is inconclusive. You can cancel the check, correct clues or try an explained step.
Will a hint guess?
The tool previews a deduction supported by its current logical rules. If no supported step is found, it says so. A logical stall is different from no solution. Applying a hint is explicit and does not reveal the entire answer.
Can I import a photo or a large puzzle?
This version accepts manually entered standard Shikaku grids from 2×2 to 9×9. It does not read screenshots or variant rules. Clue areas must sum to the number of squares. Even small grids can exceed the search budget.
What is saved or shared?
Your text draft, applied clues and explained steps are saved under a separate solver key in this browser, when storage is available. Game saves are separate. A share link includes applied clues and steps in its fragment; unfinished text edits are excluded. A shared link opens separately until you explicitly save it. Clearing browser data removes local drafts. See privacy details.