Calculate the area of squares, rectangles, circles, triangles, trapezoids, and parallelograms instantly.
An Area Calculator finds the surface area enclosed by a two-dimensional shape based on its dimensions, supporting common shapes such as squares, rectangles, circles, triangles, trapezoids, and parallelograms. It is widely used for practical tasks such as estimating how much paint, flooring, tiling, fabric, or fencing material is needed for a project, as well as for classroom geometry problems where students need a quick way to verify their manual calculations.
Each shape uses its own standard geometric formula: a rectangle's area is length x width; a square's area is side squared; a circle's area is pi x radius squared; a triangle's area is half x base x height; and a trapezoid's area is half x (base1 + base2) x height. The calculator automatically applies the correct formula once you select the shape and enter its required dimensions.
Select the shape you want to measure, then enter the relevant dimensions, for example, length and width for a rectangle, or radius for a circle. The tool instantly computes the area in your chosen unit, and most versions also let you switch between metric units like square meters and imperial units like square feet.
Example 1: A rectangular room measuring 4 meters by 5 meters has an area of 20 square meters, which is the figure you would use to estimate flooring material needed.
Example 2: A circular garden bed with a radius of 3 meters has an area of pi x 3 squared, approximately 28.27 square meters.
Standard area calculators are built around common geometric shapes with well-defined formulas; for a genuinely irregular shape, the usual approach is to break it into several simpler shapes, calculate each area separately, and add them together.
One square meter equals approximately 10.764 square feet, so multiplying a square-meter figure by 10.764 gives the equivalent in square feet, and dividing a square-foot figure by the same number converts it back.
The formula pi times radius squared uses the radius by definition; if you only know the diameter, simply halve it to get the radius before calculating, since using the diameter directly in that formula would give a result four times too large.
Area measures the amount of two-dimensional surface enclosed by a shape's boundary, while perimeter measures the total length of that boundary itself; the two use entirely different formulas even for the same shape.
Irregular polygons with many sides typically require either dividing the shape into triangles and rectangles or using the shoelace formula with the coordinates of each corner, which is beyond the scope of a basic single-shape area tool.
The calculation itself is mathematically exact for the given inputs; any error comes from how precisely the real-world dimensions were measured, so more careful measuring with a tape or laser measure will always improve the accuracy of the final area.
Yes, once the area is computed in square meters or square feet, it can be converted to acres (roughly 4,047 square meters per acre) or hectares (10,000 square meters per hectare) for land and agricultural use cases.
Materials like paint, tiles, turf, and flooring are typically sold based on coverage per square meter or square foot, so knowing the exact area helps avoid under-ordering (running short mid-project) or over-ordering (wasting money on excess material).
The simplest approach is to mentally split the L-shape into two rectangles, calculate each rectangle's area separately using length times width, and then add the two results together to get the total floor area of the room.
No, this calculator is built specifically for flat, two-dimensional shapes; surface area of 3D solids such as cubes, cylinders, or spheres uses different formulas that account for every face of the object and is handled by a dedicated surface area calculator.
A triangle is geometrically exactly half of a parallelogram with the same base and height, which is why its area formula includes that factor of one-half compared with the simpler base-times-height formula used for rectangles and parallelograms.
A parallelogram's area also uses base times height, but the height must be measured as the perpendicular distance between the two parallel bases, not the length of the slanted side, which is a common point of confusion when the shape is tilted.