⬛ Area Calculator

About this Area Calculator

This area calculator covers the five shapes you meet most often — square, rectangle, triangle, circle and trapezoid — and gives the perimeter (or circumference) at the same time. All measurements use the same unit, so if you enter metres, the area is in square metres.

How to use it

1. Pick the shape from the list.
2. Enter its measurements (the form changes to match the shape).
3. Click Calculate area to see the area and perimeter.

Example

A rectangle 8 m long and 3 m wide has an area of 24 m² and a perimeter of 22 m.

Frequently asked questions

Why does a triangle need three sides?

The area only needs the base and height, but the perimeter is the sum of all three sides, so the other two sides are asked for as well.

What units should I use?

Any single unit, as long as you use it for every measurement — centimetres give cm², metres give m².

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