Perimeter Calculator
Calculate the perimeter of a rectangle, square, circle or triangle.
Perimeter — the total distance around a shape's edge — matters for fencing, trim, borders, and any project where you need to measure the boundary rather than the enclosed space.
Perimeter vs. area — easy to confuse, very different answers
Perimeter is a single linear measurement, while area is squared. A shape can have a small area but a large perimeter (a long, thin rectangle), so always double-check which one your project actually needs.
Frequently asked questions
Is circumference the same as perimeter?
Circumference is just the term used for the perimeter of a circle specifically.
How much extra material should I buy beyond the exact perimeter?
Most projects benefit from a 5-10% buffer for waste, cuts, and mistakes.