Is this Shikaku generator free?

Yes. Pick a difficulty, generate a puzzle and print it with its answer, with no sign-up and no watermark. It is free for classroom, home and personal use.

How do I start solving one?

Start with the numbers that have only one shape. A prime number can only be a single row or a single column, and a number as wide as the grid has nowhere to slide. Then look for cells that only one rectangle can possibly reach, which is the same move the solver makes.

Does every puzzle have one solution?

Yes. A board can look perfectly reasonable and still be cuttable two ways, which makes the printed answer wrong rather than merely hard. Every puzzle here is checked by the same solver our Publisher Studio uses, so the numbers fix exactly one cut.

Does it include the answer?

Yes. Every puzzle prints as two pages: the puzzle on page one and the finished cut on page two, so you can check your work.

What size are the pages?

The free tool prints at 8.25 by 11 inches, a popular large-print size. Our Publisher Studio will export the same book at any KDP trim, from 5.06 by 7.81 up to 8.27 by 11.69, as a print-ready 300 DPI interior.

Free tool

Free Shikaku generator, with the answer

Pick a size and generate a Shikaku, then print it with its answer. Every puzzle cuts exactly one way, with no sign-up and no watermark. It runs on the same engine as our KDP Publisher Studio.

Difficulty

Bigger boards that allow bigger rectangles are harder. Every puzzle cuts one way.

8×8 board. Cut the grid into rectangles so each one holds exactly one number and has that many cells.

Two pages: the puzzle and its answer. Every puzzle is proved to cut exactly one way by the same engine as our KDP studio.

Want the whole book?

This makes one puzzle. Sign up to turn it into a full Shikaku book for Amazon KDP: hundreds of graded puzzles at any trim, as print-ready PDFs.

Build the full book

Free to build · pay once to export

Preview

The puzzle and its answer, as they print.

Shikaku Medium

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Shikaku Medium · Solution

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How to make a Shikaku puzzle

1Pick a difficulty. Choose a board. Harder grades are bigger and allow bigger rectangles, so each number has more shapes it could be.
2Generate the puzzle. Press Generate puzzle. You get a fresh board, proved to cut exactly one way.
3Print the two pages. Press Print / save PDF. You get two pages: the puzzle on page one and its answer on page two.

How to solve a shikaku

Cut the grid into rectangles so that every rectangle holds exactly one number and has exactly that many cells. Every cell ends up in one rectangle, and no rectangle may hold two numbers.

The method

1Start with the numbers that have only one shape. A prime number is a single row or a single column and nothing else, so a 5 or a 7 is already half placed. A number as wide as the grid has nowhere to slide at all.
2Use the other numbers as walls. No rectangle may contain two numbers, so a shape that would swallow a neighbouring clue is out. On a crowded board that removes more options than the sizes do.
3Look for cells only one rectangle can reach. Corners and edges are the place to look: a cell in the corner can only be covered by rectangles that reach into it, and often there is just the one. That is the same move the solver makes, and it is usually the first real foothold.
4Count what is left. The numbers always add up to the number of cells, so once a region is sealed off the clues inside it must account for exactly its area. A region that comes up short or long means something earlier is wrong.

The one rule: Rectangles only, one number in each, area equal to that number, every cell used exactly once.
What the answer page shows: The finished cut is printed at the back.
How the grades differ: Harder grades are bigger boards that allow bigger rectangles, so each number has more shapes it could be and more places each shape could sit.
Good for: Solvers who like times tables and a tidy finished page.

Publishing a whole book?

This tool makes one puzzle for home or the classroom. To make a Shikaku book you can sell on Amazon KDP, Publisher Studio generates hundreds of graded puzzles across a difficulty curve, at any KDP trim, as a print-ready interior and solutions PDF.

See the KDP Shikaku maker

Questions

What is Shikaku?: Shikaku is a Japanese logic puzzle, also called Rectangles or Divide by Box. You cut the grid into rectangles so that every rectangle holds exactly one number and has exactly that many cells. Every cell ends up in one rectangle, and no rectangle may hold two numbers.
Is this Shikaku generator free?: Yes. Pick a difficulty, generate a puzzle and print it with its answer, with no sign-up and no watermark. It is free for classroom, home and personal use.
How do I start solving one?: Start with the numbers that have only one shape. A prime number can only be a single row or a single column, and a number as wide as the grid has nowhere to slide. Then look for cells that only one rectangle can possibly reach, which is the same move the solver makes.
Does every puzzle have one solution?: Yes. A board can look perfectly reasonable and still be cuttable two ways, which makes the printed answer wrong rather than merely hard. Every puzzle here is checked by the same solver our Publisher Studio uses, so the numbers fix exactly one cut.
Does it include the answer?: Yes. Every puzzle prints as two pages: the puzzle on page one and the finished cut on page two, so you can check your work.
What size are the pages?: The free tool prints at 8.25 by 11 inches, a popular large-print size. Our Publisher Studio will export the same book at any KDP trim, from 5.06 by 7.81 up to 8.27 by 11.69, as a print-ready 300 DPI interior.

Short of ideas? Browse our ready-made printables for this puzzle and print one today.