🔲 Perimeter Calculator

Perimeter is the total length of the boundary around a 2D shape. It is measured in linear units (m, cm, ft, etc.). Think of it as the distance you would walk if you traced the outline of the shape.

Perimeter measures the boundary length of a shape (linear units), while area measures the surface it encloses (square units). A shape with a large perimeter does not necessarily have a large area.

The circumference is the perimeter of a circle. It equals 2πr (using the radius) or πd (using the diameter). For a circle with radius 7: C = 2 × π × 7 ≈ 43.98 units.

Pi (π ≈ 3.14159) is the constant ratio of any circle's circumference to its diameter. This is true for every circle regardless of size. It appears in all circle formulas because of this fundamental relationship.

For an irregular polygon, add the lengths of all sides. If you have coordinates of vertices, you can calculate the distance between consecutive points using the distance formula: d = √((x₂−x₁)² + (y₂−y₁)²), then sum all distances.