Calculate the area, perimeter, diagonal, side measurements, and other key properties of a rectangle quickly and accurately.
A Rectangle Calculator is a geometry tool that helps you calculate the most important measurements of a rectangle using its length and width.
The calculator determines the rectangle's area, perimeter, diagonal, length-to-width ratio, and interior angles. It is useful for students, teachers, construction projects, design work, and everyday measurements.
Simply enter the two side lengths and the calculator instantly provides the calculated results.
You only need two measurements to calculate the basic properties of a rectangle.
Enter the length of your rectangle into the first input field.
Enter the width of the rectangle into the second input field.
Click calculate to instantly see the area, perimeter, diagonal, and angles.
The area of a rectangle is found by multiplying its length by its width.
The perimeter is the total distance around all four sides of the rectangle.
The diagonal connects two opposite corners and can be calculated using the Pythagorean theorem.
A rectangle is a four-sided geometric shape with four right angles. Each interior angle measures exactly 90 degrees.
Opposite sides of a rectangle are equal in length and parallel to one another. The adjacent sides can have different lengths.
The diagonals of a rectangle are equal in length and bisect each other. The diagonal can be calculated from the length and width using the Pythagorean theorem.
A square is a special type of rectangle in which all four sides have equal lengths.
Suppose a rectangle has a length of 12 units and a width of 8 units.
Its perimeter is:
Its diagonal is:
A rectangle is a four-sided shape with four right angles. Its opposite sides are equal and parallel.
Multiply the length by the width. The formula is A = l × w.
Add the length and width and multiply the result by two. The formula is P = 2(l + w).
Use the Pythagorean theorem: d = √(l² + w²).
Yes. Every interior angle of a rectangle is exactly 90 degrees.
Yes. The two pairs of opposite sides are equal in length and parallel.
Yes. The calculator accepts decimal values such as 12.5, 7.25, or 15.75.
You can use any consistent unit. For example, if the length and width are in meters, the area will be in square meters.
Yes. A square meets all the defining properties of a rectangle, with the additional property that all four sides are equal.
To calculate the basic area, perimeter, and diagonal, you need the rectangle's length and width.