Geometry

Area Calculator

Calculate the area of any 2D shape: circle, rectangle, triangle, trapezoid, ellipse, parallelogram, and more.

Inputs

Shape

Dimension 1 (length / radius / base)

Dimension 2 (width / height / second base)

Dimension 3 (height / angle in ° / sides)

Results

—

Area

Perimeter / Circumference—

Formula—

Area Formulas Quick Reference

Rectangle: l × w
Circle: πr²
Triangle: ½ × base × height
Trapezoid: ½(a+b)×h
Ellipse: π × a × b
Parallelogram: base × height

What is the Area Calculator?

The Area Calculator is an all-purpose 2D geometry solver. It calculates the total flat space enclosed within the boundaries of various shapes, including rectangles, triangles, trapezoids, parallelograms, and circles.

How It Works (Formula)

Area formulas differ by polygon. A rectangle is Length multiplied by Width. A triangle is half the Base multiplied by the Height. The calculator dynamically applies the correct geometric formula based on the shape you select.

$$ A_{\text{triangle}} = \frac{1}{2} b h \quad \text{and} \quad A_{\text{trapezoid}} = \frac{a+b}{2}h $$

Geometric formulas for two common 2D polygons.

How to Use It

First, use the dropdown menu to select the specific 2D shape you are measuring. Input the required dimensional lengths (like base, height, or radius). The tool will output the total square area in your preferred units.