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How to Find the Area of a Rectangle (Mathematics Lesson)

How to Find the Area of a Rectangle

The area of a rectangle is found using the formula:



In this formula, b is the length of the base of the rectangle and h is the height of the rectangle. The image below shows what we mean by the length of the base and the height:

A Real Example of How to Find the Area of a Rectangle

An Example Question

What is the area of a rectangle with a base of 8 cm and a height of 5 cm, as shown below?

Step 1
Start with the formula:
Area = bh
Don't forget: bh = b × h

Step 2
Substitute the length of the base and the height into the formula. In our example, b = 8 and h = 5.
Area = 8 × 5 = 40 cm2
The area of the rectangle with a base of 8 cm and a height of 5 cm is 40 cm2.

Another Real Example of How to Find the Area of a Rectangle

The slider below shows another real example of how to find the area of a rectangle:
Curriculum
Geometry Lessons
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Here is an interactive widget to help you learn about finding the area of a rectangle.
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Here's a second test on finding the area of a rectangle.
Here's a third test on finding the area of a rectangle.
Note

What Is a Rectangle?

A rectangle is a flat shape with four straight sides and four right angles.

The opposite sides are parallel and of equal length. Adjacent sides are perpendicular and of unequal length.

A Note on Units

The area of a rectangle is a length times a length, so we say its dimension is length2. (All areas are lengths squared.)

This affects the units used. If the lengths of a rectangle are in cm, the area is in cm2. If the lengths are in inches, the area is in inches2.