September 4, 2026
Daily
Play Shikaku puzzles free online. A new daily Shikaku every day, a permanent archive, and 600+ rectangle puzzles from 5x5 to 20x20. No signup, works on mobile.
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.
Shikaku is a Japanese logic puzzle published by Nikoli since 1989 under the name 四角に切れ (Shikaku ni kire — "divide by squares"). You may also know it as Rectangles, Divide by Box, or Sikaku. The rules fit in one sentence: divide the grid into rectangles so that every rectangle contains exactly one number, and that number equals the rectangle's area. A 6 lives in a rectangle of six cells — 1×6, 6×1, 2×3, or 3×2 — and when every cell on the board belongs to exactly one rectangle, the puzzle is solved.
What makes Shikaku special among grid puzzles is how geometric the logic feels. There is no arithmetic to carry and nothing to memorize; instead you reason about space. A prime number can only be a thin strip. A clue crowded against a wall has nowhere to grow but inward. Two large clues competing for the same corridor can each claim only what the other must leave behind. Good boards resolve like a chain of small proofs, and finishing one leaves the grid tiled in clean, colorful blocks.
Every puzzle on this site is generated and then machine-verified to have exactly one solution, then graded by a solver that mimics human technique: easy boards fall to singles and forced rectangles, while medium and hard boards demand common-cell deductions and orphan-prevention thinking. You never have to guess — if you're stuck, a forced move is always waiting somewhere.
Play the shared daily Shikaku to build a streak, browse the permanent archive of past dailies, or work through more than 600 free puzzles across five board sizes, from one-minute 5×5 warm-ups to hour-long 20×20 giants. No account, no downloads — it works in any browser, on phones as well as desktops, and your progress saves automatically.
A new Shikaku every day
One shared daily board on a gentle weekday-to-weekend difficulty curve — plus a permanent archive of every past daily.
Five board sizes
From quick 5×5 warm-ups to giant 20×20 marathons, with easy, medium, and hard tiers at every size.
Every puzzle verified unique
Each board is machine-checked to have exactly one solution — you never have to guess.
Autosave & shareable links
Progress saves in your browser automatically, and every board has a permanent URL you can send to anyone.