📐 Area of a Rectangle Calculator
Calculate the area, perimeter, and diagonal of a rectangle
How to Use This Calculator
Enter Length and Width
Input the length and width of your rectangle in the respective input fields. Make sure both values are positive numbers.
Click Calculate
Press the "Calculate" button to compute the area, perimeter, and diagonal of your rectangle.
Review Results
View the calculated area (in square units), perimeter, and diagonal length displayed below.
Formula
Area = Length × Width
Perimeter = 2 × (Length + Width)
Diagonal = √(Length² + Width²)
Where:
- Length (l) = the longer side of the rectangle
- Width (w) = the shorter side of the rectangle
- Area = the space enclosed by the rectangle
Example: Calculate the area of a rectangle with length = 10 units and width = 5 units
Area = Length × Width
Area = 10 × 5
Area = 50 square units
About Area of a Rectangle Calculator
The Area of a Rectangle Calculator helps you quickly find the area, perimeter, and diagonal of any rectangle. A rectangle is a four-sided polygon with opposite sides equal and all angles equal to 90 degrees.
When to Use This Calculator
- Construction & Architecture: Calculate floor area, wall area, or material requirements
- Landscaping: Determine garden area, lawn coverage, or paving requirements
- Interior Design: Calculate room area for flooring, painting, or furniture placement
- Education: Learn and practice geometry calculations
- Real Estate: Calculate property area and dimensions
- Engineering: Design calculations for rectangular components
Why Use Our Calculator?
- ✅ Instant Results: Get area, perimeter, and diagonal instantly
- ✅ Multiple Calculations: Calculate area, perimeter, and diagonal in one go
- ✅ Step-by-Step Display: See the calculation formula applied to your values
- ✅ Works with Any Units: Works with meters, feet, inches, or any unit of measurement
- ✅ 100% Accurate: Precise mathematical calculations
- ✅ Completely Free: No registration required
Understanding Rectangle Properties
A rectangle is a special type of parallelogram where all angles are right angles (90°). Key properties:
- Opposite sides are equal in length and parallel
- All four angles are right angles (90 degrees)
- Diagonals are equal in length and bisect each other
- Area is the product of length and width
- Perimeter is twice the sum of length and width
Real-World Applications
Flooring: To tile a rectangular room that is 12 feet long and 8 feet wide, you need 12 × 8 = 96 square feet of tiles.
Fencing: To fence a rectangular yard measuring 50 meters by 30 meters, you need a perimeter of 2 × (50 + 30) = 160 meters of fencing material.
Painting: To paint a wall that is 10 feet tall and 15 feet wide, you need to cover 10 × 15 = 150 square feet.
Frequently Asked Questions
What is the formula for the area of a rectangle?
The area of a rectangle is calculated by multiplying its length by its width: Area = Length × Width.
Can I use different units for length and width?
Yes, but make sure both dimensions use the same units for accurate results. For example, if length is in meters, width should also be in meters. The area will be in square meters.
What's the difference between length and width?
In a rectangle, length is typically the longer side and width is the shorter side. However, mathematically, either can be considered length or width as long as you're consistent. The area calculation works the same either way.
How do I find the perimeter of a rectangle?
The perimeter is calculated as: Perimeter = 2 × (Length + Width). This represents the total distance around the rectangle.
How is the diagonal of a rectangle calculated?
The diagonal is calculated using the Pythagorean theorem: Diagonal = √(Length² + Width²). This gives the length of the line connecting opposite corners.
What if my rectangle is actually a square?
A square is a special rectangle where length equals width. The area formula still applies: Area = side × side = side². Our calculator works perfectly for squares too!
Can I calculate area if I only know the perimeter?
No, you need both length and width to calculate the area. If you only know the perimeter, you have one equation with two unknowns, so you'd need additional information (like the ratio of length to width) to find the area.