Rectangles Solver

Rectangles Solver — Step by Step

Choose the rows and columns, click a square and type its number to copy in your puzzle, then press Solve. Or play a generated puzzle and send it here with one click.

Rectangles Solver: rules, how to use it, tips

Split the grid into rectangles so each holds exactly one number, and that number is its area.

The rules

Divide the whole grid into rectangles (squares are rectangles too).
Every rectangle contains exactly one number.
The number is the rectangle’s area — how many squares it covers.
Every puzzle has exactly one solution.

Using the solver

Choose the number of rows and columns, then click each numbered square and type its number (or press Sample).
Press Solve and step through: one shape left, only one number can reach a square, squares every shape shares, and shapes that would block another number.

Tips

Factor pairs. List the shapes a number can take: 12 is 1×12, 2×6, 3×4, 4×3, 6×2 or 12×1. Shapes that run off the grid or swallow another number are out.
Primes are strips. A prime number like 5 or 7 can only be a straight line, one square thick.
Corners and edges. A square in a corner may be reachable by only one number — that number’s rectangle must stretch to it.
Shared squares. If every possible shape for a number covers the same squares, those squares are its, and no other rectangle can use them.

The full guide, with a worked example and common mistakes: How to play Rectangles.

Questions

Is this the same as Shikaku?

Yes — Shikaku is the Japanese name for the same puzzle.

What maths does it practise?

Multiplication facts and factor pairs (which widths and heights make each number), area, and checking with addition: all the numbers together add up to the size of the grid.

Can a rectangle be a square?

Yes. A 4 can be a 2×2 square, a 9 can be 3×3.

How do I enter a puzzle from a book?

Open the Rectangles Solver, choose the rows and columns, click each numbered square and type its number, then press Solve.