Surface Area of a Rectangle Calculator
Calculate rectangle area, perimeter, and diagonal with step-by-step solutions
Calculate Rectangle Properties
Usually the longer side of the rectangle
Usually the shorter side of the rectangle
Rectangle Formulas
Surface Area: A = ℓ × w
Perimeter: P = 2(ℓ + w)
Diagonal: d = √(ℓ² + w²)
where ℓ = length, w = width
Example Calculations
Example 1: Basic Rectangle
Given: length = 5 m, width = 2 m
Area: 5 × 2 = 10 m²
Perimeter: 2 × (5 + 2) = 14 m
Diagonal: √(5² + 2²) = 5.39 m
Example 2: Monitor Screen
Given: length = 15.6 in, width = 8.8 in
Area: 15.6 × 8.8 = 137.28 in²
Perimeter: 2 × (15.6 + 8.8) = 48.8 in
Diagonal: √(15.6² + 8.8²) = 17.9 in
Quick Reference
Key Formulas
Area = ℓ × w
Perimeter = 2(ℓ + w)
Diagonal = √(ℓ² + w²)
Unit Conversions
1 m = 3.281 ft
1 ft = 12 in
1 m = 100 cm
1 cm = 10 mm
Rectangle Properties
Quick Tips
Length is usually the longer dimension
Ensure both dimensions use the same units
Area is measured in square units (unit²)
Perimeter is the distance around the edge
Understanding Rectangle Surface Area
What is a Rectangle?
A rectangle is a quadrilateral (four-sided polygon) with four right angles. Opposite sides are equal in length and parallel to each other. Since it's a 2D shape, the term "surface area" is often simply called "area."
The Formula
The surface area formula A = ℓ × w comes from the basic principle that area represents the amount of space inside a shape. For rectangles, this is simply the product of length and width.
Step-by-Step Process
Step 1: Identify Dimensions
Measure or identify the length and width
Step 2: Check Units
Ensure both measurements use the same units
Step 3: Multiply
Calculate A = length × width
Real-World Applications
Construction:
Calculate flooring, roofing, or wall area for material estimation
Technology:
Determine screen area for monitors, tablets, and smartphones
Gardening:
Plan garden beds, calculate seed coverage, or estimate lawn area