Rectangle Calculator
Calculate area, perimeter, and diagonal of any rectangle instantly
Calculation Results
Enter rectangle measurements to calculate all properties.
Length: units
Width: units
Area: square units
Perimeter: units
Diagonal: units
Rectangle Diagram
The Rectangle: A Fundamental Geometric Shape
A rectangle is a basic geometric figure that falls under the category of quadrilaterals. It has four sides, with opposite sides equal in length and four right angles (each measuring 90 degrees).
Key Properties of a Rectangle
- Length (l) - The longer side of the rectangle.
- Width (w) - The shorter side of the rectangle.
- Perimeter (P) - Total distance around the rectangle (P = 2(l + w)).
- Area (A) - The space enclosed within the rectangle (A = l × w).
- Diagonals - Two diagonals of equal length that bisect each other (d = √(l² + w²)).
- Angles - All four interior angles are 90°.
- Symmetry - A rectangle has 2 lines of symmetry and 180° rotational symmetry.
Mathematical Equations of a Rectangle
- Perimeter
P = 2(l + w) - Area
A = l × w - Diagonal
d = √(l² + w²)
Why Are Rectangles Important?
- Design & Layout - Used in page layouts, screens, paper sizes, and furniture.
- Mathematics - Found in coordinate geometry, area calculations, and algebra.
- Construction & Engineering - Common in floor plans, walls, and architectural blueprints.
- Everyday Life - Seen in books, TVs, smartphones, doors, and windows.
Facts About Rectangles
- The word "rectangle" comes from Latin "rectangulus" (meaning "right angle").
- A rectangle with equal length and width is a square.
- Rectangles are the basis for most 2D screen displays and UI layouts.
Rectangles are all around us—in designs, devices, and architecture. Understanding their properties is essential for solving practical and theoretical problems in geometry and beyond.
Rectangle Formulas
- Length (l): l = A/w = (P/2) - w
- Width (w): w = A/l = (P/2) - l
- Area (A): A = l × w
- Perimeter (P): P = 2(l + w)
- Diagonal (d): d = √(l² + w²)
Note: √ denotes square root.
Length (l)
Width (w)
Area (A)
Diagonal (d)
How to Use the Rectangle Calculator
This Rectangle Calculator helps you compute properties like area, perimeter, and diagonal based on what you already know.
1 Select the Input Type
Choose the known values:
- Length (l) and Width (w)
- Area (A) and one side
- Perimeter (P) and one side
- Diagonal (d) and one side
Example: If you know length and width, select both and input the values.
2 Enter the Known Value(s)
Input valid numbers for the selected fields.
- Use positive values, decimals allowed (e.g., 5.5).
Example: Length = 8, Width = 4
3 Click "Calculate"
Click Calculate to compute the following:
- Area (A)
- Perimeter (P)
- Diagonal (d)
Example Output:
- Area = 32
- Perimeter = 24
- Diagonal ≈ 8.94
Example Use Cases
- Estimating floor area of rectangular rooms.
- Finding diagonal screen size for monitors and TVs.
- Calculating fencing for rectangular plots.
Example Calculations
-
Example 1: Length = 10 units, Width = 4 units:
- Area = 40 units²
- Perimeter = 28 units
- Diagonal ≈ 10.77 units
-
Example 2: Area = 60 units², Width = 6 units:
- Length = 10 units
- Perimeter = 32 units
- Diagonal ≈ 11.66 units
-
Example 3: Diagonal = 13 units, Width = 5 units:
- Length ≈ 12 units
- Area ≈ 60 units²
- Perimeter ≈ 34 units
Frequently Asked Questions
Area is calculated as:
A = l × w
A square has all sides equal; a rectangle has equal opposite sides, but adjacent sides can differ in length.
Use the formula:
d = √(l² + w²)
- Architecture: Floor plans, doors, and windows
- Technology: Screens, papers, layouts
- Mathematics: Graphs, geometry problems
- Interior design: Furniture and storage planning