Area of Shapes

Compute the area of a rectangle, triangle, circle or trapezoid — pick the shape and its inputs change. One calculator for the four everyday planar figures.

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Worked example

Area: 40

How it’s solved

Worked on the example above, step by step — follow along and you can do it on paper next time, no tool required.

A rectangle's area is simply width times height.
Multiply width by height
10 × 4 = 40

Learn the method

Inputs

Shape
Rectangle / Triangle / Circle / Trapezoid
Width
10
Height
4
Base
6
Triangle height
8
Radius
5
Trapezoid a
4
Trapezoid b
8
Trapezoid height
3

Frequently asked

What shapes are supported?

Rectangle (w × h), triangle (½ × base × height), circle (πr²) and trapezoid ((a+b)/2 × h).

Do the input fields change per shape?

Yes — choosing a shape shows only the measurements that shape needs.