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Population Growth Rate Calculator
Calculate how a population changed between two observations. Enter the same geographic area at two dates to see total growth, compound annual growth, the numeric change, and an estimated doubling time when growth is positive.
Population growth calculator
Use comparable estimates for the same place and population definition.
Population growth rate formula
Total growth is ((ending population ÷ starting population) − 1) × 100. Annual growth uses the compound annual growth rate formula: (ending ÷ starting)1 ÷ years − 1. Compounding matters because a 10% increase over five years is not the same as growing 2% in every year.
How to choose comparable inputs
Both numbers should describe the same boundaries and population concept. A city may annex land, a statistical area may be redefined, and an estimate can use a different reference date than a census count. Those changes can look like population growth even when they are partly measurement changes. Check the source notes before comparing two values.
Growth, decline, and doubling time
A positive annual rate produces a doubling-time estimate using logarithms. It answers a narrow hypothetical question: how long would doubling take if the calculated rate continued unchanged? It is not a forecast. The calculator leaves doubling time blank for zero or negative growth because a declining population does not double at that rate.
What drives the result
Population change is usually explained by births, deaths, and net migration. The calculator measures the combined outcome but cannot identify which component caused it. A place can also grow in total while particular age groups shrink, so planning questions often require demographic detail beyond a headline growth rate.
For U.S. estimates, consult the U.S. Census Bureau Population Estimates Program. For international comparisons, the World Bank population series provides country-level data with source notes.
Frequently asked questions
How do you calculate population growth rate?
Divide the ending population by the starting population, raise the ratio to one divided by the number of years, subtract one, and convert the result to a percentage.
What does population doubling time mean?
Doubling time estimates how long a population would take to double if the calculated annual compound growth rate continued unchanged.