Frequently Asked Questions

Perimeter is the total distance around the edge of a shape. It's calculated by adding up the lengths of all sides. For example, a rectangle's perimeter = 2(length + width), while a circle's perimeter (circumference) = 2πr.

Our calculator supports rectangles, circles, triangles, squares, regular polygons, and ellipses. Each shape has its own specific formula and input requirements.

You can use any unit of measurement (inches, centimeters, meters, feet, etc.). Just make sure to use the same unit for all measurements of the same shape. The result will be in the same units you input.

This happens when the triangle inequality theorem is violated. For any triangle, the sum of any two sides must be greater than the third side. For example, sides of 3, 4, and 10 cannot form a triangle because 3 + 4 = 7, which is less than 10.

Radius is the distance from the center of a circle to its edge. Diameter is the distance across the entire circle through its center. Diameter = 2 × radius. You can enter either value in our calculator.

Our calculations are mathematically accurate to 2 decimal places. For circles and ellipses, we use the precise value of π (pi) for maximum accuracy. The ellipse calculation uses Ramanujan's approximation, which is highly accurate for most practical purposes.

Yes! This calculator is perfect for students, teachers, and anyone learning geometry. It shows step-by-step calculations and formulas to help you understand the process, not just get the answer.

Yes, this perimeter calculator is completely free to use. There are no subscriptions, registrations, or hidden fees. You can use it as many times as you need for personal, educational, or professional purposes.

Yes! Our calculator is fully responsive and works perfectly on smartphones, tablets, and desktop computers. The interface automatically adapts to your screen size for the best user experience.