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Calcimator

Perimeter Calculator

Calculate the perimeter of rectangles, circles (circumference), triangles, and regular polygons with any number of sides.

Inputs

units
units

Results

Perimeter

30 units

Formula UsedP = 2(l + w)
How to Use This Calculator
  1. Select the shape (rectangle, circle, equilateral triangle, or regular polygon) from the Shape dropdown.
  2. Enter the required dimensions for your shape — length and width for rectangles, radius for circles, or a single side length for equilateral triangles and regular polygons.
  3. Perimeter formulas: rectangle = 2(l+w); circle (circumference) = 2πr; equilateral triangle = 3s; regular polygon = n × s.
  4. For a regular polygon, also set the number of sides (at least 3) alongside the side length.
  5. Perimeter and area are different — perimeter is the boundary length, area is the enclosed region.
  6. All dimension inputs must be positive; for polygons, the number of sides must be at least 3.

How the result changes with Length / Radius / Side

Length / Radius / SidePerimeter
10,00020,010 units
35,00070,010 units
65,000130,010 units
90,000180,010 units

What each input means

Shape
The geometric shape to calculate.
Length / Radius / Side
Length of the shape or side.
Width
Used for rectangles.
Number of Sides
Used for regular polygons.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Shape = 0, Length / Radius / Side = 10, Width = 5, Number of Sides = 6 = 4 input(s) provided
  2. Calculate Perimeter
    Perimeter
    30 = 30
  3. Calculate Formula Used
    Formula Used
    P = 2(l + w) = P = 2(l + w)

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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