Perimeter Calculator — Any Shape
Perimeter / Circumference
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Formula Used
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How to Calculate the Perimeter of Any Shape
The perimeter is the total distance around the outside of a two-dimensional shape. For polygons, it is the sum of all side lengths. For circles, the perimeter is called the circumference and equals 2 times pi times the radius (C = 2piR).
Common perimeter formulas: Rectangle P = 2(L+W), Square P = 4s, Triangle P = a+b+c, Circle C = 2piR. For irregular shapes, measure each side individually and add them up. The perimeter is always expressed in linear units (meters, feet, inches).
Perimeter calculations are essential in everyday life - from measuring fencing needed for a yard, to calculating trim for a room, to determining the border length for a garden bed. This calculator handles the most common shapes with instant results.
Frequently Asked Questions
What is the difference between perimeter and area?
Perimeter measures the distance around the outside of a shape (in linear units like meters), while area measures the space inside the shape (in square units like square meters).
How do you find the perimeter of an irregular shape?
Measure each side individually and add all the lengths together. For curved sections, you may need to use string or a flexible measuring tape to follow the curve.
Is circumference the same as perimeter?
Yes. Circumference is simply the specific name for the perimeter of a circle. The formula is C = 2piR or C = piD, where R is the radius and D is the diameter.