Area & Perimeter Calculator
Free area and perimeter calculator. Calculate the area and perimeter of circles, triangles, rectangles, squares, trapezoids, parallelograms, and other geometric shapes with formulas and diagrams.
How to Calculate Area and Perimeter
Area measures the surface of a shape in square units, while perimeter measures the total length of its boundary. Each geometric figure has specific formulas. This calculator supports the most common shapes: circle, triangle, rectangle, square, and trapezoid.
Key Formulas
Circle: Area = πr², Perimeter = 2πr. Rectangle: Area = base × height, Perimeter = 2(base + height). Triangle: Area = (base × height) / 2. Square: Area = side², Perimeter = 4 × side.
Frequently Asked Questions
How do I calculate the area of a triangle?
The area of a triangle is base times height divided by 2. If you know all three sides, you can use Heron's formula instead.
What is the difference between area and perimeter?
Area measures the interior surface of a shape (in square units), while perimeter measures the total length of its boundary (in linear units).