How To Calculate Area

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carpet fitter measuring roomWhat is area?

Area tells us the size of a shape or figure. It tells us the size of squares, rectangles, circles, triangles, other polygons, or any enclosed figure.

In the real world it tells us the size of pieces of paper, computer screens, rooms in houses, baseball fields, towns, cities, countries, and so on. Knowing the area can be very important. Think of getting a new carpet fitted in a room in your home. Knowing the area of the room will help make sure that the carpet you buy is big enough without having too much left over.

Calculating Area

Area is measured in squares (or square units).

How many squares are in this rectangle?

example of rectangle with area of 15 square units

We can count the squares or we can take the length and width and use multiplication. The rectangle above has an area of 15 square units.


The area of a rectangle is = length x width

Examples of calculating the area of a rectangle

3 by 2 rectangle

Area = Length x Width

Area = 3 x 2 = 6 square units

8 by 6 rectangle

Area = Length x Width

Area = 8 x 6 = 48 square units

9 by 5 rectangle

Area = Length x Width

Area = 9 x 5 = 45 square units

Units for measuring area

We measure area using squares. We use different sizes of squares depending on how big or small an area is.

Example Length of side on Squares Unit

Size of the nail on your thumb



Size of piece of paper



Size of a room



Size of a town




Don't forget the wee 2

We write square sizes using a small 2 next to the unit.

We write mm2, cm2, m2 , km2, cm2

We can say "63 millimeters squared" or " 63 square millimeters"

We could use small squares to measure large areas. The only problem with this is that we would end up having to use very big numbers. For example, a field might be measured at 5,000,000,000 square millimeters when 5,000 square meters would be a much easier size to say, write, and visualize.

You will probably hear more units for measuring area; square inches, square feet, square yards, square miles, acres, hectares are all units used for measuring area.

More Examples of Calculating Area of Rectangles

9 by 4 mmm rectangle

Area = Length x Width

Area = 9 mm x 4 mm = 36 mm2

6 by 7 cm rectangle

Area = Length x Width

Area = 7 cm x 6 cm = 42 cm2

2 by 8 m rectangle

Area = Length x Width

Area = 8 m x 2 m = 16 m2

5 by 7 km rectangle

Area = Length x Width

Area = 7 km x 5 km = 35 km2

Area of a Square

The length and width of a square are the same so we just need to multiply the length by the length.

6 by 6 cm square

Area = Length x Length

Area = 6 cm x 6 cm = 36 cm2

Calculating Area Worksheets

Print out the worksheets listed below and use them for practice when learning how to calculate the area of squares and rectangles.

You will find more printable geometry worksheets here.

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