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How to use Perimeter Calculator

Choose the shape, enter its side lengths or radius, and the perimeter or circumference is calculated instantly with the formula displayed.

Frequently asked questions

What is the difference between perimeter and circumference?

Perimeter is the total distance around a straight-sided shape; circumference is that same distance for a circle, found with 2 × π × r.

Can it handle a rectangle?

Yes — enter length and width and it returns 2 × (length + width) as the perimeter.

Which shapes are supported?

Square, rectangle, triangle, circle, parallelogram, trapezoid, rhombus, regular polygon and more, each with its own formula.

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