Rectangle Area Calculator
Enter the rectangle's length and width to find its area instantly.
What Is the Area of a Rectangle?
The area of a rectangle tells you how much two-dimensional space is inside it. Imagine laying tiles on a floor: the area is the amount of space those tiles cover. In math, area is measured in square units, such as square centimeters (cm2), square meters (m2), or square feet (ft2).
A rectangle has two pairs of equal sides. One side is usually called the length, and the adjacent side is the width. Once you know these two values in the same unit, finding area is straightforward.
The Formula You Need
Area Formula
Area = Length × Width
- Length = the longer side (or one chosen side)
- Width = the shorter side (or the side next to the length)
- Result = square units
If your measurements are in meters, your answer will be in square meters. If your measurements are in inches, your answer will be in square inches.
Step-by-Step: How to Calculate Area
Step 1: Measure the Length
Use a ruler, measuring tape, or known value to identify the rectangle's length.
Step 2: Measure the Width
Measure the side next to the length. Make sure both measurements use the same unit.
Step 3: Multiply
Multiply length by width. The product is the area.
Step 4: Add the Correct Unit
Write your answer with a squared unit symbol. For example, 24 m2, 48 cm2, or 90 ft2.
Worked Examples
Example 1: Whole Numbers
Length = 9 cm, Width = 4 cm
Area = 9 × 4 = 36 cm2
Example 2: Decimal Values
Length = 7.5 m, Width = 2.4 m
Area = 7.5 × 2.4 = 18 m2
Example 3: Real-World Flooring
A room is 15 ft long and 12 ft wide.
Area = 15 × 12 = 180 ft2
You would need flooring for approximately 180 square feet (usually with extra for cuts and waste).
Common Mistakes to Avoid
- Mixing units: Don’t multiply meters by centimeters without converting first.
- Forgetting the squared unit: Area is always square units, not just units.
- Using perimeter formula by accident: Perimeter is 2(L + W), not L × W.
- Input errors: Double-check decimal points and typed values in calculators.
Where Rectangle Area Is Used in Everyday Life
- Buying paint for walls and ceilings
- Estimating tile, carpet, or laminate flooring
- Planning garden beds and lawns
- Designing posters, banners, and signs
- Cutting glass, wood, and sheet materials
Area vs. Perimeter: Quick Difference
People often confuse area and perimeter. Here is the simple distinction:
- Area: space inside a shape (square units)
- Perimeter: distance around a shape (linear units)
For a rectangle with length 10 and width 6:
- Area = 10 × 6 = 60 square units
- Perimeter = 2(10 + 6) = 32 units
Practice Problems
Try these quickly, then check your answers:
- Length 11 cm, Width 3 cm → Area = 33 cm2
- Length 14 m, Width 9 m → Area = 126 m2
- Length 2.5 ft, Width 1.2 ft → Area = 3 ft2
Final Takeaway
To calculate the area of a rectangle, multiply length by width and include square units in your final result. That’s it. Use the calculator above to save time and avoid arithmetic mistakes, especially when working with decimals.