Perimeter Calculator
Calculate the perimeter or circumference of rectangles, squares, circles, and triangles with ease.
About this Calculator
Calculate the perimeter or circumference of rectangles, squares, circles, and triangles with ease.
Formula & Calculations
Formula
Rectangle: P = 2(l+w); Square: P = 4s; Circle: C = 2πr; Triangle: P = a+b+cWhere:
- P=Perimeter or circumference
- l=Length (rectangle)
- w=Width (rectangle)
- s=Side length (square)
- r=Radius (circle)
- a, b, c=Side lengths (triangle)
Assumptions
- All measurements use consistent units; output perimeter uses the same unit.
- Circle circumference uses π ≈ 3.1415926535.
Calculation Examples
Example 1
Inputs:Shape: Rectangle, Length: 12, Width: 8
Result:40 units
2 × (12 + 8) = 2 × 20 = 40 units.
Example 2
Inputs:Shape: Circle, Radius: 5
Result:31.42 units
2 × π × 5 ≈ 31.42 units.
Frequently Asked Questions
What is the difference between perimeter and circumference?
Perimeter refers to the distance around a polygon (rectangle, square, triangle), while circumference specifically refers to the distance around a circle.
Can I calculate the perimeter of a triangle if I only know two sides?
No, you need all three side lengths to calculate a triangle's perimeter, unless you also know the triangle type (e.g., isosceles or equilateral) to infer the third side.