Q:
# How do you calculate population growth?

**Subtracting a past population value from the present population value, and dividing this result by the past population value, yields the population-growth rate.** Multiplying the population-growth rate by 100 yields the growth percentage.

Credit:
Creativited
Stone
Getty Images

Population growth is a change in population size during a particular time period. In the simplest calculation, growth rate is equal to [P(t2) - P(t1)]/P(t1), where P(t1) is a past population value and P(t2) is the present population. This calculation yields a growth rate for any chosen time range. It is common to express growth rate as a percentage by multiplying the rate by 100. Dividing the percent population growth by the number of years between t1 and t2 gives an annual growth percentage. For example, a population that experiences 10 percent growth in 10 years has a 1 percent annual growth rate.

The population growth calculation is also an excellent tool for predicting future populations, given a known growth rate. In this case P(t2) is a future population, and the unknown variable, and P(t1) is the present population.

Another method of predicting a future population is to find doubling time. Doubling time is the result of dividing 70 by the percent growth. In this calculation 70 is a constant that derives from the natural log of 2.

Learn more about Population & Demography-
Q:
## How much has the world population grown each year?

A: Average annual 20th century population growth peaked in 1987 at approximately 92.3 million people, but the average annual 20th century growth rate peaked i... Full Answer >Filed Under: -
Q:
## How do I calculate a population's growth rate?

A: 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 ... Full Answer >Filed Under: -
Q:
## When do populations grow exponentially?

A: Populations grow exponentially when they can maintain a constant growth rate percentage and can leverage the steady increase in population. Exponential gro... Full Answer >Filed Under: -
Q:
## How do you calculate mortality rate?

A: The mortality rate is calculated by taking all the deaths that occurred during a particular time period and dividing that number by the total size of the p... Full Answer >Filed Under: