Rectangle Area Calculator

Enter length and width to calculate rectangular area.

Length

Width

—Rectangle geometry

—Area

—Perimeter

—Diagonal

Rectangle reverse solve, perimeter & diagonal

Use the rectangle relation in both directions instead of only multiplying two inputs. Solve from length × width or recover one missing side from area, then cross-check perimeter, diagonal and aspect ratio in a consistent unit.

Solve modeLengthWidthAreaLinear unit

—Area

—Perimeter

—Diagonal

—Aspect ratio

Ready.

Check	Value	Relation	Use

All three linear quantities use the selected unit and area uses its squared form. Reverse solving assumes a positive non-zero known side.

Use consistent measurements and valid geometric assumptions

Keep linear inputs in a consistent unit, verify that side lengths or coordinate points can form the stated shape, and treat sketches as explanatory unless explicitly marked to scale. Coordinate formulas can become unstable for nearly degenerate shapes, so invalid or nearly collinear inputs are rejected rather than silently returning misleading values.