Perimeter Calculator
Calculate the perimeter of a rectangle, circle or triangle.
Result
Results are estimates for general information only and are not professional advice.
Perimeter formulas
The perimeter is the total distance around a shape. A rectangle is 2 × (width + height), a circle's perimeter (circumference) is 2 × π × radius, and a triangle is the sum of its three sides. Choose a shape and enter the values.
Frequently Asked Questions
What is the Perimeter Calculator?
Calculate the perimeter of a rectangle, circle or triangle. It runs instantly in your browser and is completely free to use.
What do I need to enter to use the Perimeter Calculator?
The Perimeter Calculator asks for the following values (4): Shape, Width / Radius / Side a, Height / Side b, Side c (triangle). Fill them in and the result appears immediately — the calculation runs on your own device, so nothing you type is sent to a server.
How accurate is the Perimeter Calculator?
The Perimeter Calculator uses standard, widely-accepted formulas, so its figures are reliable estimates for everyday planning. They are not a substitute for advice from a qualified professional.
Is the Perimeter Calculator free, and do I need an account?
Yes. The Perimeter Calculator — and every other calculator on Calculatis — is completely free, with no registration, no download and no limit on how often you use it.