Rectangle Calculator – Calculate Area, Perimeter, Diagonal, and Sides

length width Rectangle Calculation Area = length × width Measurements: - Result: -
Formula
Area = length × width
Enter values to calculate
Rectangle Area

This is a versatile tool for performing various calculations related to the geometric properties of a rectangle. You can calculate the area, find a missing side length using the perimeter or diagonal, or determine the dimensions of a square from its area.

Calculation Methods

The calculator supports several modes to fit your needs:

  • Length & Width: The most common calculation. Enter the length and width to find the rectangle's area.
  • Area (reverse calc): Enter a known area to find the side length, width, and perimeter, assuming the shape is a perfect square.
  • Perimeter & Width: If you know the total perimeter and the width of a rectangle, this mode calculates the corresponding length.
  • Diagonal & Width: Uses the Pythagorean theorem to find the length of a rectangle when its diagonal and width are known.

Formulas Used

Key Rectangle Formulas:
Area (A): A = length (l) × width (w)
Perimeter (P): P = 2 × (l + w)
Diagonal (d): d = √(l2 + w2)
Formulas for Reverse Calculations:
Length from Perimeter: l = (P / 2) - w
Length from Diagonal: l = √(d2 - w2)

Usage Examples

  1. Finding Area: A room has a length of 15 ft and a width of 10 ft. Its area is 150 ft2.
  2. Using Different Units: A garden plot is 5 meters long and 200 centimeters wide. The calculator will correctly determine the area as 10 m2.
  3. Finding Length from Perimeter: A fence has a total perimeter of 100 meters, and one side (width) is 20 meters. The length of the other side is 30 meters.
  4. Finding Length from Diagonal: A screen has a diagonal of 50 inches and a width of 30 inches. Its length will be 40 inches.
  5. Reverse Calculation from Area: A square field has an area of 2500 m2. The calculator determines that its length and width are both 50 m, and its perimeter is 200 m.
  6. Small-Scale Example: A microchip measures 5 mm in length and 2 mm in width. The area is 10 mm2.
  7. Large-Scale Example: A rectangular piece of land is 1.5 km long and 0.5 km wide. Its area is 0.75 km2.
Privacy Assurance: All calculations are performed directly in your browser. No data is sent to or stored on our servers.