Learn how to calculate the perimeter of a rhombus using the formula P = 4s, where s is the length of a side. Also, find the area of a rhombus using the formula A = 1/2 d1 d2, where d1 and d2 are the diagonals. Perimeter of a rhombus is the sum of all its sides. Perimeter of a rhombus with side “a” is given by 4a. Learn the definition, formulas, and examples. Perimeter of a Rhombus is the sum of all the sides of the rhombus . In a rhombus , all the sides are equal so the perimeter of the rhombus is 4 times its side. The perimeter of Rhombus is calculated by the formula P = 4a where a is the side length of the perimeter . Now we can also find the perimeter of the rhombus with diagonals. A rhombus is a specific type of parallelogram because it satisfies the requirement that a parallelogram is a quadrilateral with two sets of parallel sides. A rhombus has two lines of symmetry, which are its two diagonals. A line that divides a thing into two equally sized halves is called an axis of symmetry. A rhombus ’ perimeter equals the total of all of its sides. All four sides of a rhombus are the same length, making it a quadrilateral.