How to calculate the Area of a Square or Rectangle

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This is a simple math tutorial aimed at middle school students, explaining how to calculate the area of a square or rectangle (and the reasoning behind the two available methods).


Introduction

Squares and rectangles are two types of four-sided shapes, or quadrangles. We will cover how to calculate the area of another type of quadrangle, called a parallelogram, in the next tutorial.


What do we mean by 'area'?

Describing the area of a square or rectangle is a way of describing how much space is within the shape.

The units that we use to describe that space is called the square unit. A square unit is quite literally the shape of a square. The area that you calculate and report for a shape tells you how many of those square units would fit in that space.


How to calculate the area of a square or rectangle

There are two methods that you can use to calculate the area of a square or rectangle.

  1. Count the number of square units that fit into the shape, and
  2. Multiply the shape's width by its height.

Method 1

The first method is the simplest to understand. You can see below how each square unit has been numbered off in both the rectangle and square. The area for each shape is 16 square units.


Method 2

The second method is a little faster and is transferable to parallelograms. It uses the formula:

Area of square or rectangle = width x height

 
We can see this in practice below:


Different types of square units

Depending on how large that square is, we can call the unit by slightly different names. If the square is a metre wide and a metre high, we'd call it a square metre. If it was a centimetre high and wide, we'd call it a square centimetre. Similarly, if it was a mile high and a mile wide, we'd call it a square mile.

Complementary Exercises

Now that you know how to calculate the area of a square and a rectangle, why not consolidate your understanding by having a go at some simple exercises? You can access them (and their worked out answers) here: