Pick a board size
Use square or rectangular boards from 4x4 up to 10x10.
Solver
Shikaku Solver
Interactive
6 x 6
Click any cell, enter its clue number, and run the solver. The clue sum must equal the full board area.
How to Use
Enter clue cells
Click a cell on the board, then enter the area number. Desktop supports direct keyboard input; mobile uses the on-page keypad.
Run the solver
The solver checks legal rectangles and searches for a full non-overlapping partition.
What This Shikaku Solver Does
This tool lets you enter any Shikaku board by clue positions and clue values, then checks whether the puzzle can be partitioned into valid rectangles. It is built for players who want help on a stuck puzzle and for puzzle authors who want a fast validity check before publishing a board.
Unlike a simple answer viewer, this solver enumerates legal rectangles for each clue and then searches for a full, non-overlapping covering of the board.
When the Solver Helps
Check if a puzzle is solvable
If the clue sum matches the board area, the solver can test whether at least one full rectangle partition exists.
Inspect candidate pressure
The candidate panel shows how many legal rectangles each clue can take before overlap constraints are applied.
Review multiple solutions
If a board is not unique, you can cycle through the first few solutions and compare how the partitions differ.
Frequently Asked Questions
Does every Shikaku puzzle have a unique solution?
No. A puzzle can have one valid rectangle partition, multiple valid partitions, or no valid partition at all if the clues are inconsistent.
Why does the clue sum need to match the board area?
Each clue is the area of exactly one rectangle. If the total clue area does not equal the board area, the board cannot be fully covered.
Can I use the solver for the daily puzzle?
Yes. Use the Load Today's Daily button to import the current deterministic daily board and reveal a valid partition.
Will this page connect to backend APIs later?
Yes. The page is designed so puzzle validation, hint generation, analytics, and archive lookups can later move to backend endpoints without changing the page structure.