Get Started

Area Calculator

Compute area of common shapes like rectangles, circles, triangles, trapezoids, and ellipses.

units
Longer side.
units
Shorter side.
²
cm, m, ft, in, etc.
Area result—
Area —
Formula used —
Perimeter / circumference —
Shape —
Input A—
Input B—
Input C—
Unit—

Use the same unit for every measurement before calculating area.

How it works

Understand area calculations

This Area Calculator helps you calculate the surface covered by common two-dimensional shapes. You can switch between rectangle, circle, triangle, trapezoid, and ellipse, then enter the required measurements for that shape.

The result includes the area, the exact formula used, and a related perimeter or circumference value where it can be calculated from the information provided. This makes the tool useful for schoolwork, construction planning, DIY projects, layout design, and quick geometry checks.

Choose the correct shape

Area formulas are different for every shape, so the first step is choosing the shape that matches your real object or diagram. A rectangle uses length and width, a circle uses radius, a triangle uses base and height, and a trapezoid uses two parallel bases plus height.

Keep units consistent

All measurements should use the same unit before calculating. If one side is measured in meters and another in centimeters, convert them first; otherwise the final square-unit result will be misleading.

Review the formula

The calculator displays the formula used for the selected shape. This helps you understand the steps, verify your work, and copy the method into notes, homework, project estimates, or reports.

Use area practically

Area is useful for estimating flooring, paint coverage, fabric, land size, screen space, garden beds, classroom geometry, and layout planning. The calculator gives a quick answer but still depends on accurate measurements.

Frequently asked questions

Rectangle area is calculated by multiplying length × width. For example, if a room is 12 meters long and 8 meters wide, the area is 96 square meters. The calculator also shows perimeter, which is useful when estimating borders, fencing, trim, or edging.
Circle area is calculated with π × radius². The radius is the distance from the center of the circle to its edge. If you only know the diameter, divide the diameter by 2 first, then enter that radius into the calculator.
Triangle height is the perpendicular distance from the base to the opposite point. It is not always the same as a slanted side. If the height is not drawn directly, you may need to find it from the diagram or use another triangle formula.
Yes. The calculator can work with any measurement unit as long as all inputs use the same unit. If your inputs are in feet, the result is square feet. If your inputs are in centimeters, the result is square centimeters.
Area measures a two-dimensional surface, so the unit is squared. A length is measured in cm, m, ft, or in, but an area is measured in cm², m², ft², or in² because it covers both width and height.
For a triangle or trapezoid, base and height alone are enough to calculate area, but not enough to calculate every outer side. To find the exact perimeter, you need the lengths of all sides.