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
- Select the shape (rectangle, square, circle, triangle, or regular polygon) from the Shape dropdown.
- Enter the required dimensions for your shape β length and width for rectangles, radius for circles, or side length and number of sides for regular polygons.
- Perimeter formulas: rectangle = 2(l+w); circle (circumference) = 2Οr; regular polygon = n Γ s.
- For a triangle, three side lengths are needed; the calculator sums them and checks the triangle inequality.
- Perimeter and area are different β perimeter is the boundary length, area is the enclosed region.
- All dimension inputs must be positive; for polygons, the number of sides must be at least 3.
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