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Perimeter Formulas

Last updated date: 05th Mar 2024
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Perimeter is an important fundamental topic in mathematics defined as the distance of a boundary around the shape. It is the algebraic sum of the length of every side of the object. It allows you to quantify the physical space and give a foundation for advanced mathematics in algebra, calculus, and trigonometry.

For a two-dimensional shape, the perimeter is the total distance around the shape. If you have a ball and a thread with you, then wrap the thread around that ball. The total distance that the thread covers is the perimeter of the ball. Latest find out the perimeter formulas of various shapes available in the geometry.

Perimeter Formulas

The use of perimeter is applied daily by engineers, architects, and graphic designers, and so it is much needed by people generally. It helps you understand the total space you have to learn to fit different shapes all together in the file you are constructing or painting a model.

1. The Perimeter of Rectangle Formula:  A rectangle is a shape whose angles are equal to 90 degrees or right angles, and the opposite sides are equal.

Perimeter of rectangle = 2 (a + b) = 2a + 2b

a & b (length and width of the sides of a rectangle)

2. The Perimeter of the Triangle Formula: A triangle is a shape that has three straight lines with three angles. There are three types of triangles.

  • Equilateral Triangle: The perimeter of equilateral triangle = 3 a.

  • Isosceles Triangle: Perimeter of isosceles triangle = 2s + b.

  • Scalene Triangle: Perimeter of scalene triangle = a + b + c.

3. The Perimeter of the Square Formula: A square is a shape whose all the angles are equal to 90 degrees or right angle, and all four sides are equal.

The perimeter of a square is equal to 4 × a = 4a.

Where a is the length of the square's side.

4. The Circle Formula’s Perimeter: A circle is a round shape that has no edges or corners.

Perimeter of a circle = 2 × π × r = 2πr = πd

r (radius of circle)

d (diameter of the circle)

5. The Perimeter of Semicircle Formula: A semicircle is the algebraic sum of half the circle’s circumference and diameter.

Perimeter of a circle = 2 × π × r = 2πr = πd

Perimeter of a semicircle = ½ (πd + d) or πr + 2r

r (radius of semicircle)

6. The Perimeter of Rhombus Formula:  A rhombus is defined as a parallelogram whose all sides are equal.

Perimeter of rhombus = 4 × a = 4a.

7. The Perimeter of the Parallelogram Formula: A parallelogram is a shape that looks like a quadrilateral (opposite sides parallel to each other).

Perimeter of parallelogram = 2 (a + b).

a & b (length and width of the sides of a parallelogram).

8. The Trapezoid Formula’s Perimeter: A trapezoid is a shape that is equal to quadrilateral and has a minimum of one pair of parallel sides.

Perimeter of trapezoid = a1 + a2 + b1 + b2.

a & b (length and width of the sides of a trapezoid).


As described above, the perimeter of a 2-D shape is the total distance around that shape. You will get the result of a shape after adding all its sides (same unit). Many formulas have been developed to find the area of standard shapes very quickly.

FAQs on Perimeter Formulas

1. Why is Perimeter Important in Mathematics?

Ans: Perimeter is a physical aspect of mathematics that is essential as a basic two geometrical aspect like theorem’s, which will help students understand algebra, trigonometry, and calculus. It is used everywhere in day-to-day lives, such as fencing a plot, construction of a house, covering rooms with the carpet, farming, etc.

2. What is the Perimeter of a Polygon?

Ans: Polygon is a shape whose each number of sides and angles are equal.

The perimeter of a polygon = n × s.

3. What is the Area of a House Plot with a Parameter of 320m?

Ans: The house plot's shape is a square at the perimeter = 320m.

So the length of each side = 320 ÷ 4 = 80m.