Rectangle Length, Width & Area Calculator

Calculate any missing rectangle value -- length, width, or area -- when you know two of the three.

What Do You Want to Find?

Result

Area
--
square units
Length --
Width --
Area --
Perimeter --
Diagonal --

Step-by-Step Solution

A = L x W

Rectangle Length, Width, and Area Relationships

A rectangle is one of the most fundamental shapes in geometry. It is defined by two dimensions -- length and width -- which together determine all other properties of the rectangle. Understanding the relationships between these values is essential for solving problems in geometry, architecture, and everyday calculations.

Key Rectangle Formulas

Area

The space enclosed within the rectangle.

A = Length x Width

Length from Area

Find the length when area and width are known.

L = Area / Width

Width from Area

Find the width when area and length are known.

W = Area / Length

Perimeter

The total distance around the rectangle.

P = 2(L + W)

Diagonal

The distance between opposite corners.

d = sqrt(L^2 + W^2)

When to Use Each Calculation

Finding Area

The most common calculation is finding the area when you know both the length and width. This is used for calculating floor space, material requirements, painting areas, and land measurements.

Finding Length or Width

When you know the area and one dimension, you can find the missing dimension. This is useful when planning rooms of a specific area, determining material dimensions for a required coverage, or reverse-engineering specifications from area constraints.

Practical Applications

  • Construction: Calculating room dimensions, flooring, and wall coverage.
  • Gardening: Determining plot sizes and material needs.
  • Design: Sizing images, screens, and print media.
  • Real Estate: Understanding lot sizes and building footprints.
  • Manufacturing: Cutting materials to required dimensions.