Rectangle Area Calculator
What Is Area?
Area is a measurement that describes how much space a flat, two-dimensional shape occupies on a surface. You can think of it as the amount of material required to completely cover a shape, such as paint covering a wall or grass covering a field.
In geometry, area represents the two-dimensional counterpart of other measurements. A line has length, a solid object has volume, and a flat figure has area.
The standard unit for measuring area in the International System of Units (SI) is the square meter (m²). This unit represents the area of a square with sides that each measure one meter.
Different shapes have different formulas for calculating their area. Below are some of the most common geometric figures and the equations used to determine their area.
Rectangle
A rectangle is a four-sided polygon where every interior angle is exactly 90 degrees. Opposite sides are equal in length and run parallel to each other.
To find the area of a rectangle, you only need two measurements:
- Length – the longer side of the rectangle
- Width – the shorter side of the rectangle
Once these two values are known, calculating the area is straightforward.
Formula
Area = Length × Width
If both sides happen to be the same length, the rectangle becomes a special case called a square.
Example: A Farmer’s Rectangular Field
Consider a farmer who owns a rectangular piece of land and wants to determine its size. The boundaries of the field are fenced, so the farmer knows the exact dimensions of the plot.
Because the farmer lives in the United States, the measurements are recorded in feet rather than meters. Today, one foot is defined as exactly 0.3048 meters, although historically the length of a foot varied across regions and time periods.
Suppose the field measures:
- Length: 220 feet
- Width: 99 feet
Using the rectangle area formula:
Area = length × width
Area = 220 × 99
Area = 21,780 square feet
This means the farmer’s field covers 21,780 square feet of land.
For comparison, one acre equals 43,560 square feet, meaning the field is roughly half an acre in size.
Even though the farmer knows the exact size of his property, selling it proves difficult. Some potential buyers prefer measurements in different units, which sometimes leads to confusion when comparing land sizes across different systems of measurement.