Perimeter Calculator

Perimeter or circumference for common shapes — fencing, trim, borders.

Perimeter Calculator helps you perimeter or circumference for common shapes — fencing, trim, borders. Enter length / side / radius, width / side b, and side c / sides count, review the breakdown, and use the guidance below to understand what the number means — and what it does not. What the Perimeter calculator does Perimeter Calculator is built for arithmetic, algebra, geometry, and number tools. Perimeter or circumference for common shapes — fencing, trim, borders. You enter length / side / radius, width / side b, and side c / sides count, then Simple Calculators computes the result instantly. Results use standard school and engineering formulas that run privately in your browser. How the math works Pick a Length unit (metres by default) and a Shape, then enter its sides. Rectangle = 2 × (length + width), square = 4 × side, triangle = side a + side b + side c, circle = 2 × π × radius, parallelogram = 2 × (side a + side b) and regular polygon = number of sides × side length. The ellipse uses Ramanujan’s close approximation from its semi-major and semi-minor axes (half the longest and shortest widths). The answer is also converted to metres and feet, with the enclosed area shown fo…