To determine the square footage of a rectangle, multiply the length by the width. The answer is in given square units. For example, if a lawn is 20 feet by 30 feet, the measurement is 600 square feet. This is also referred to as "area."
The measurement is always described in square units. It does not matter if the object is measured in miles, yards, feet, inches, kilometers, meters, centimeters or millimeters. Some professionals need to be able to calculate square footage in their daily work. For instance, painters must first know the area of the room they are going to paint in order to purchase the correct amount of paint.