Area of a Rectangle

Area of a Rectangle

The formula is given below.

Rectangle labeled with height and width. Formula: Area = (height)(width)

See also

Key Formula

A = l \times w

Where:

$A$ = Area of the rectangle (in square units)
$l$ = Length of the rectangle
$w$ = Width of the rectangle

Worked Example

Problem: Find the area of a rectangle with a length of 8 cm and a width of 5 cm.

Step 1: Write down the formula for the area of a rectangle.

A = l \times w

Step 2: Substitute the given values into the formula.

A = 8 \times 5

Step 3: Multiply to find the area.

A = 40 \text{ cm}^2

Answer: The area of the rectangle is 40 cm².

Why It Matters

Calculating the area of a rectangle is one of the most frequently used skills in everyday life and in more advanced math. You need it to determine how much paint covers a wall, how much carpet fits a room, or how large a screen is. It also serves as the foundation for finding the areas of more complex shapes like triangles, trapezoids, and composite figures.

Common Mistakes

Mistake: Forgetting to use square units in the answer (writing 40 cm instead of 40 cm²).

Correction: Area measures two-dimensional space, so the units are always squared. If the sides are in centimeters, the area is in square centimeters (cm²).

Related Terms

Rectangle — The shape whose area this formula calculates
Formula — A general rule expressed with symbols
Area — The broader concept of measuring enclosed space
Perimeter of a Rectangle — Measures the distance around the rectangle instead
Square — A special rectangle where length equals width