Calculate perimeter for squares, rectangles, triangles, circles, parallelograms, and trapezoids.
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Geometry
The perimeter calculator finds the perimeter (total boundary length) of squares, rectangles, triangles, circles, parallelograms, and trapezoids from their dimensions.
Square: 4 times side. Rectangle: 2(length + width). Triangle: sum of three sides. Circle (circumference): 2 pi r. Parallelogram: 2(base + side). Trapezoid: sum of all four sides.
For circles, the perimeter is called the circumference. All other shapes use the sum of their side lengths.
This calculator covers regular shapes. For irregular polygons, sum the individual side lengths manually.
Frequently asked questions
Perimeter is the total length around the boundary of a shape (measured in linear units). Area is the space enclosed within the boundary (measured in square units).
The circumference is 2 times pi times the radius, or pi times the diameter.
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