Which shapes are supported?

Rectangle, square, triangle (base × height), circle, trapezoid, parallelogram and ellipse. Each uses its standard geometric area formula.

What units does the result use?

The calculator is unit-agnostic — whatever unit you enter for the lengths, the area comes out in those units squared (for example metres in gives metres² out).

How do I find the area of a circle?

Use area = π × r², where r is the radius. For a circle of radius 5, the area is π × 25 ≈ 78.54 square units. Select "circle" in the tool and enter the radius.

What is the formula for the area of a trapezoid?

A trapezoid's area is ½ × (a + b) × h, where a and b are the two parallel sides and h is the perpendicular height between them.

Area Calculator — Gera Tools

Q: Is anything uploaded?

No — every calculation runs entirely in your browser and nothing is sent to a server.

The Area Calculator works out the area of the most common geometric shapes — rectangle, square, triangle, circle, trapezoid, parallelogram and ellipse — in one place. It is useful for homework, DIY and construction estimates, flooring and paint quantities, and any time you need a quick, accurate area without looking up the formula.

How it works

You pick a shape, enter its dimensions, and the calculator applies that shape’s standard geometric formula. The tool is unit-agnostic: whatever unit you type the lengths in, the area comes back in that unit squared (metres in → metres² out).

Shape	Formula
Rectangle	width × height
Square	side × side
Triangle	½ × base × height
Circle	π × radius²
Trapezoid	½ × (a + b) × height
Parallelogram	base × height
Ellipse	π × a × b (semi-axes)

Example

A circle with a radius of 5 m:

Area = π × 5² = π × 25 ≈ 78.54 m².

A rectangle measuring 4 m by 3 m has an area of 4 × 3 = 12 m².

Every calculation runs entirely in your browser and nothing is uploaded.