About Shikaku
Play Shikaku online for free. Divide the entire grid into rectangles (including squares) so that every rectangle contains exactly one numbered clue, and that clue equals the rectangle's area in cells. A Nikoli classic built on pure spatial logic.
The Rules
Divide the grid into rectangles so that each rectangle contains exactly one number, matching its area.
Step by Step
- Every numbered cell is a clue: the rectangle containing it must have exactly that many total cells.
- Draw rectangles by dragging from one corner to another — rectangles cannot overlap.
- Every cell in the grid must end up inside exactly one rectangle.
- The puzzle is solved when every rectangle contains exactly one clue matching its area, and the whole grid is covered.
Tips & Strategy
- Start with clues that have few factor pairs — a clue like 7 can only form a 1×7 or 7×1 rectangle.
- Large clues near the edge of the grid are heavily constrained by how much space is actually available.
- Work from the corners and edges inward — they have the fewest possible rectangle shapes to consider.
- Two clues close together can only both be satisfied if their rectangles fit side by side without overlapping — use that to rule out shapes early.
Frequently Asked Questions
What does a clue number mean in Shikaku?
It's the exact number of cells the rectangle containing that clue must cover.
Can rectangles overlap or leave gaps?
No — every cell in the grid must belong to exactly one rectangle, with no overlaps and no gaps.
Can a rectangle be a square?
Yes — a square is just a rectangle with equal sides, so any clue with a perfect-square area (4, 9, 16...) can also form a square region.
