How to Play Shikaku
Divide the grid into non-overlapping rectangles. Each rectangle must contain exactly one number, and that number equals the rectangle's area.
Try it now — Easy 8x8 →The Rules
- Divide the entire grid into non-overlapping rectangles
- Each rectangle contains exactly one number clue
- The number equals the area (total cells) of the rectangle
- Every cell belongs to exactly one rectangle — no gaps
Available in 4 sizes (6x6, 8x8, 10x10, 14x14) and 3 difficulty levels (easy, normal, hard).
See It in Action
Draw a rectangle around each number — the area must equal the number inside
How to Play
- Factor each number to find all possible rectangle dimensions (e.g. 6 → 1×6, 2×3, 3×2, 6×1)
- Start with clues in corners and along edges — fewer orientation choices are available there
- Sketch rectangle outlines and check they don't overlap or leave uncovered cells
- Adjust whenever two rectangles conflict by trying an alternative shape for one of them
Pro Tips
Prime numbers (2, 3, 5, 7...) can only form very thin rectangles — they're easy to place
A rectangle can never contain two number clues — use this to rule out placements
Work from the most constrained clue (fewest valid shapes) to the least constrained
Frequently Asked Questions
What is Shikaku?
Shikaku is a logic puzzle where you divide a grid into rectangles. Every cell must be in exactly one rectangle, each rectangle contains exactly one number, and that number equals the area (number of cells) of the rectangle.
Choose Your Challenge
Start with easy to learn the rules, then progress to harder difficulties.