Q:

# How do you calculate population growth?

A:

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.

Know More

## Keep Learning

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.

Sources:

## Related Questions

• A:

To calculate percent sales growth over a period, subtract the previous sales figure from the current sales figure, divide the result by the previous sales figure, and then multiply this number by 100, explains Michael Marz for the Houston Chronicle. In order to obtain the most accurate growth percentage, be sure to use net sales figures. Calculate net sales by taking the total gross sales and subtracting discounts, refunds and any other expenses.

Filed Under:
• A:

The Business Dictionary defines exponential growth as an increase in number or size at a constantly increasing rate. Math Planet explains that exponential growth is represented by an exponential function, which is a nonlinear function with the form, y = ab^x, where a does not equal zero and b is greater than zero. The graph of any exponential growth function rises from left to right in a curved line.

Filed Under:
• A:

An aging population refers to a phenomenon in which the median age of the population in a region or country rises significantly when compared to the total population. This is caused by a declining birth rate or rising life expectancy.