Calculate rectangle area, perimeter, and diagonal
80.00
sq ft
36.00
ft
12.81
ft
Area = length × widthThe area of a rectangle is the product of its length and width.
Where:
length= The longer side of the rectanglewidth= The shorter side of the rectanglePerimeter = 2 × (length + width)The total distance around the rectangle.
Where:
length= The longer side of the rectanglewidth= The shorter side of the rectangleDiagonal = √(length² + width²)The diagonal length using the Pythagorean theorem.
Where:
length= The longer side of the rectanglewidth= The shorter side of the rectangleInputs
Result
Area = 10 × 8 = 80.00. Perimeter = 2 × (10 + 8) = 36.00. Diagonal = √(10² + 8²) = √(100 + 64) = √164 = 12.81.
Inputs
Result
Area = 15 × 6 = 90.00. Perimeter = 2 × (15 + 6) = 42.00. Diagonal = √(15² + 6²) = √(225 + 36) = √261 = 16.16.
Area of a rectangle = length × width. For example, a rectangle with length 10 and width 8 has area = 10 × 8 = 80 square units.
Perimeter = 2 × (length + width). For a rectangle with length 10 and width 8, perimeter = 2 × (10 + 8) = 36 units. Alternatively, add all four sides: length + width + length + width.
Diagonal = √(length² + width²). Using the Pythagorean theorem, for a rectangle with length 10 and width 8, diagonal = √(10² + 8²) = √164 = 12.81 units.
A square is a special type of rectangle where all four sides are equal. In a square, length = width, so area = side² and perimeter = 4 × side. A rectangle has two pairs of equal sides but they don't have to be the same length.
A rectangle has four right angles and opposite sides that are equal. The area is length times width.
The perimeter is twice the sum of length and width. The diagonal can be found using the Pythagorean theorem.
A square is a special rectangle where length equals width, simplifying all calculations.
Last Updated: Feb 12, 2026
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