Singles
EasySome clues have exactly one rectangle that fits. Every 1 is a single cell. A 2 with only one free neighbor is done. Scan for these first — each placement is free information, because its edges become walls for every clue around it.
Guide
Shikaku rules in plain English: one clue per rectangle, clue = area, cover the grid. Quick-start steps, named techniques, and FAQ — free to play.
Divide the grid into rectangles and squares along the gridlines.
Every rectangle must contain exactly one number.
That number equals the rectangle's area — a 6 sits in a rectangle covering exactly 6 cells (1×6, 2×3, 3×2, or 6×1).
Rectangles fill the whole board with no gaps and no overlaps.
Every puzzle has exactly one solution, so you never need to guess — draw by dragging from one corner of a rectangle to the opposite corner.
Learn the rules in under a minute, then solve your first board.
Each number on the grid belongs to one rectangle, and the number tells you that rectangle's exact area in cells. A 1 is a single cell; a 6 covers six cells.
Start where only one rectangle can fit: 1s are instant, prime numbers must be thin strips, and clues pressed against an edge or corner have few ways to grow.
Press on one corner cell and drag to the opposite corner — the preview shows the area live. On touch you can also tap a corner, then tap the opposite corner. The number dims when its rectangle matches.
Every cell must end up inside exactly one rectangle, each containing one matching number. When the last cell is covered correctly, the board is solved — share your time or jump to the next puzzle.
Every board here is verified to a single solution and graded by which of these techniques it needs: easy boards fall to the first five, medium boards demand common-cell deduction, and hard boards demand orphan prevention and region logic. When you stall, walk this list top to bottom — one of them always applies. Most of the ladder also carries over to Patches, the LinkedIn-style descendant whose clues name a shape as well as an area; our sister site sets the two rule sets side by side in Patches vs. Shikaku on Patches Game.
Some clues have exactly one rectangle that fits. Every 1 is a single cell. A 2 with only one free neighbor is done. Scan for these first — each placement is free information, because its edges become walls for every clue around it.
Look at empty cells, not just clues: if only one clue's possible rectangles can reach a cell, that clue MUST cover it — which usually pins the rectangle's direction or position. Cells hugging walls and corners are the best place to spot this.
A prime number (2, 3, 5, 7, 11, 13…) can only form a 1×n strip. On a 10-wide board an 11 must run vertically… or not exist; a 7 has just two orientations, and other clues in its row or column often eliminate one of them instantly.
A clue near the board's edge has less room to grow: a 9 in a corner may only fit as a 3×3 square, and a 6 pressed against a wall loses half its shapes. Work the border first — it's where boards unravel.
A rectangle may never contain two numbers. Rule out every candidate that would swallow a neighboring clue — in crowded areas this alone can cut a clue from six candidates to one.
When every remaining candidate for a clue overlaps on certain cells, those cells belong to that clue no matter which candidate is right. Claim them mentally: no other clue's rectangle may cross them, which forces hands elsewhere. Medium boards require this move.
A placement is wrong if it would strand a cell no remaining rectangle can reach. Before committing a big rectangle, check the cells it walls off — and when you spot an almost-enclosed empty cell, the one rectangle that can still reach it is forced. Hard boards turn on this.
Solved rectangles carve the board into independent regions. The clue areas inside a region must sum exactly to its cell count — if a candidate would split off a region whose clues cannot pay for its cells, that candidate is dead. This closes out the giant boards.