Calculate population growth rate by dividing the change in population by the initial population, multiplying it by 100, and then dividing it by the number of years over which that change took place. The number is expressed as a percentage.
Population growth rates are used for many sizes of geographic areas from a specific neighborhood to the world. These rates take into account the births and deaths occurring during the specified time along with people who move into and out of the area.
The world population first reached 1 billion in 1804 and took more than a century to double. It grew from 4.4 billion to 6 billion between the years 1980 and 2000. In 2014, it was estimated at 7.2 billion. By 2024, it is projected to be greater than 8 billion.