Area Calculator

Each shape has its own formula. For example, a rectangle uses length × width, a circle uses π × r², and a triangle uses ½ × base × height. Select your shape from the dropdown, enter the required measurements, and this calculator applies the correct formula automatically.

There are multiple ways: if you know the base and height, use Area = ½ × base × height. If you know all three sides (a, b, c), use Heron's formula: Area = √(s(s−a)(s−b)(s−c)) where s = (a+b+c)/2. Both methods are supported here.

The area of a circle is A = π × r², where r is the radius. If you know the diameter instead, divide it by 2 to get the radius first. For a semicircle, divide the result by 2; for a quarter circle, divide by 4.

A sector is a 'pizza slice' portion of a circle defined by a radius and a central angle. Its area is A = (θ/360) × π × r², where θ is the angle in degrees and r is the radius.

The area of a trapezoid is A = ½ × (top base + bottom base) × height. You need both parallel sides (the two bases) and the perpendicular height between them.

A circle has one radius (equal in all directions), while an ellipse has two axes: a semi-major axis (a, the longer half) and a semi-minor axis (b, the shorter half). Area of an ellipse = π × a × b. When a = b, it becomes a circle.

Area is always a two-dimensional measurement, so units are always squared (e.g., m², cm², ft²). If you input dimensions in meters, the area comes out in square meters (m²). Make sure all your inputs use the same unit to get a valid result.

This tool covers 16+ standard geometric shapes. For truly irregular shapes, a common approach is to break the shape into simpler components (rectangles, triangles, etc.), calculate each area separately, and then add them together.