A 4-sided polygon where all interior angles are 90°
Try this Drag the orange dots on each vertex to reshape the rectangle.

The rectangle, like the square, is one of the most commonly known quadrilaterals. It is defined as having all four interior angles 90° (right angles).

Properties of a rectangle

  • Opposite sides are parallel and congruent Adjust the rectangle above and satisfy yourself that this is so.
  • The diagonals bisect each other
  • The diagonals are congruent


Side 1 clear
Side 2 clear

Use the calculator on the right to calculate the properties of a rectangle.

Enter the two side lengths and the rest will be calculated. For example, enter the two side lengths. The area, perimeter and diagonal lengths will be found.

Other ways to think about rectangles

A rectangle can be thought about in other ways:

  • A square is a special case of a rectangle where all four sides are the same length. Adjust the rectangle above to create a square.
  • It is also a special case of a parallelogram but with extra limitation that the angles are fixed at 90°. See Parallelogram definition and adjust the parallelogram to create a rectangle.

Coordinate Geometry

In coordinate geometry, a rectangle has all the same properties described here, but also, the coordinates of its vertices (corners) are known. See Rectangle (Coordinate Geometry) for more.

Other rectangle pages:

Area of a rectangle
Perimeter of a rectangle
Golden rectangle
Rectangle (Coordinate Geometry)

Other polygon topics


Types of polygon

Area of various polygon types

Perimeter of various polygon types

Angles associated with polygons

Named polygons