Shikaku Puzzle — play free online
Shikaku (also called Rectangles or Divide by Squares) is a Japanese logic puzzle: split the grid into rectangles so that each one contains exactly one number, and that number equals its area. Drag across the grid to draw a rectangle.
- Unique solution, every time
- 6 sizes · 3 levels
- Hints that explain
- No sign-up
0 rectangles · Drag to draw · Tap a rectangle to erase · Ctrl+Z undo · H hint
What is Shikaku?
Shikaku is a pencil-and-paper logic puzzle in which you divide a rectangular grid into smaller rectangles and squares. Every rectangle must contain exactly one number, and that number is the rectangle’s area. It was invented by Yoshinao Anpuku and first published by the Japanese puzzle company Nikoli in 1989.
Like Sudoku, Shikaku needs no maths beyond small multiplication and no guessing — a well-made puzzle always has one solution you can reach by logic. Learn the full rules in our how-to-play guide, or read about its history at Nikoli.
Divide the whole grid
Split every cell of the grid into rectangles (squares count too). No cell is left over and no rectangles overlap.
One number per rectangle
Each rectangle must contain exactly one number — never zero, never two.
The number is the area
The number tells you how many cells its rectangle covers. A 6 can be 1×6, 6×1, 2×3 or 3×2.
Shikaku puzzles from 5×5 to 25×25
Each size has Easy, Medium and Hard puzzles, and millions of possible grids. Your progress on every size is saved automatically.
Daily, weekly and monthly Shikaku
Everyone gets the same grid, so you can compare times with friends. Solve the daily puzzle on consecutive days to grow your streak.
Solve like an expert
Most of Shikaku comes down to a handful of patterns: numbers in corners, prime numbers that can only be straight lines, cells that only one number can reach, and cells that every option of a number shares.
- Start with big numbers and corners
- Prime numbers are always 1-wide strips
- Find cells only one number can reach
- Claim cells shared by every option
Built for people who love logic puzzles
Unique solutions, proven
Every grid passes an exhaustive solver check, so pure logic always works.
Graded by technique
Easy, Medium and Hard are measured by the reasoning a puzzle needs, not just its size.
Smart drawing
Live size labels, colour feedback when a rectangle fits, and automatic overlap replacement.
Hints that teach
Hints point at the most forced rectangle first and tell you why it is forced.
Undo, redo, check, pause
Unlimited undo history, mistake highlighting, timer pause and saved progress.
Play anywhere
Touch, mouse and full keyboard support, dark mode, and a layout made for phones.
Daily, weekly, monthly
Shared challenges with countdowns and a daily streak tracker.
Print & solve
Print any puzzle, or make a printable book of up to 12 puzzles with answer keys.
Free solver
Type in a Shikaku from a newspaper or app and get the solution with a uniqueness check.
Shikaku FAQ
What is a Shikaku puzzle?
Shikaku is a Japanese logic puzzle published by Nikoli in which you divide a grid into rectangles and squares. Each rectangle must contain exactly one number, and that number equals the rectangle’s area in cells. A correct puzzle has exactly one solution and can be solved by logic alone, without guessing.
How do you play Shikaku online here?
Press on a cell and drag to another cell to draw a rectangle between them. A live label shows the size, and the outline turns green when the shape fits a number. Tap any rectangle to erase it, or use the Eraser, Undo and Redo buttons. On a keyboard, move with the arrow keys and press Enter to start and finish a rectangle.
What does the word Shikaku mean?
Shikaku (四角) is Japanese for “square” or “four corners”. The full Nikoli name, Shikaku ni Kire (四角に切れ), roughly means “divide by squares” or “cut into rectangles”. In English the puzzle is also called Rectangles, Divide by Squares or Divide by Box.
Does every puzzle on PuzzleShikaku have a unique solution?
Yes. Every puzzle is built by our generator and then checked by an exhaustive solver that proves there is exactly one valid way to split the grid. If a candidate puzzle has two solutions, it is rejected or reworked before you ever see it.
How hard is Shikaku?
Small grids like 5×5 take a minute or two and are ideal for learning. Medium 10×10 and 15×15 puzzles need overlap reasoning, and our hard 20×20 and 25×25 puzzles can take an hour. Easy puzzles on this site are guaranteed to be solvable with only basic deductions.
Is PuzzleShikaku free?
Yes. Every size, the daily, weekly and monthly challenges, the printable sheets and the online Shikaku solver are free to use, with no account needed. Your progress and statistics are saved in your own browser.