Rectangle Area Calculator
Calculate rectangle area, perimeter, diagonal, and all related properties with our advanced calculator. Get instant results with step-by-step solutions and comprehensive explanations.
What is a Rectangle?
A rectangle is a quadrilateral (four-sided polygon) with four right angles (90°). It has two pairs of parallel sides, where opposite sides are equal in length. The rectangle is one of the most fundamental shapes in geometry and architecture.
Rectangles are everywhere in our daily lives - from books and screens to buildings and rooms. Understanding rectangle calculations is essential for construction, design, and many practical applications.
Rectangle Properties & Components
Length (l)
The longer side of the rectangle, typically measured horizontally.
Width (w)
The shorter side of the rectangle, typically measured vertically.
Area (A)
The space enclosed within the rectangle (A = l × w).
Perimeter (P)
The distance around the rectangle's boundary (P = 2(l + w)).
Rectangle Formulas
Area Formula
Where A is area, l is length, w is width
Perimeter Formula
Where P is perimeter, l is length, w is width
Diagonal Formula
Where d is diagonal, l is length, w is width
Length from Area
Calculate length when area and width are known
Real-World Applications
🏠 Construction & Architecture
Calculating floor areas, wall surfaces, window sizes, and material requirements for rectangular structures.
🌿 Landscaping & Gardening
Planning rectangular gardens, calculating lawn areas, designing patios, and determining fencing requirements.
📐 Interior Design
Room planning, furniture placement, carpet sizing, and optimizing space utilization in rectangular rooms.
📱 Technology & Screens
Screen dimensions, display areas, aspect ratios, and calculating pixel densities for rectangular displays.
📦 Packaging & Shipping
Box dimensions, packaging efficiency, shipping calculations, and storage optimization.
🎨 Art & Graphics
Canvas sizes, frame dimensions, print layouts, and graphic design proportions.
Special Rectangle Types
Square
A special rectangle where all sides are equal (l = w). Area = s², Perimeter = 4s, Diagonal = s√2
Every square is a rectangle, but not every rectangle is a square.
Golden Rectangle
A rectangle where the ratio of length to width equals the golden ratio (φ ≈ 1.618). Found in art, architecture, and nature.
Ratio: l/w = (1 + √5)/2 ≈ 1.618
Tips & Common Mistakes
✅ Helpful Tips
- •Always identify which measurement is length and which is width
- •Use consistent units throughout your calculations
- •Remember that area is in square units, perimeter in linear units
- •Use the Pythagorean theorem for diagonal calculations
- •Double-check your measurements before calculating
❌ Common Mistakes
- •Confusing area and perimeter formulas
- •Forgetting to use consistent units of measurement
- •Mixing up length and width in calculations
- •Not squaring both dimensions in diagonal formula
- •Assuming all rectangles are squares