Population Growth Rate Calculator: Annual Rate of Change
Work out how fast a population is changing by reducing two census counts to a single annual growth rate.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Annual growth rate | Total population change |
|---|---|---|
| 80,000 to 95,000 over 10yr | 1.73% | 18.75% |
| 1,200,000 to 1,500,000 over 20yr | 1.12% | 25.00% |
| 50,000 to 44,000 over 8yr | -1.59% | -12.00% |
| 10,000 to 26,000 over 30yr | 3.24% | 160.00% |
How This Calculator Works
Enter the population at the start and end of a period, and the number of years between the counts. The calculator finds the compound annual growth rate — the steady yearly pace linking the two — and the total change over the period.
The Formula
Compound Annual Growth Rate
Start is the beginning value, End is the ending value, n is the number of years
Worked Example
A town growing from 80,000 to 95,000 over 10 years has an annual growth rate of about 1.73%. The total change is 18.75%, but the annual rate is what lets one place be compared with another.
Key Insight
Population compounds like money. A rate near 1.7% a year sounds small, yet it doubles a population in roughly 40 years — which is why even modest annual rates reshape a place over a generation.
Frequently Asked Questions
How is a population growth rate calculated?
It is the compound annual rate between two population counts. The calculator divides the ending count by the starting count, takes the per-year root, and subtracts one.
Why use an annual rate instead of total change?
Total change depends on how long the period is. The annual rate puts places and periods of different lengths on a comparable footing.
Does this account for migration?
Not separately. It captures the net result of births, deaths, and migration combined, since it uses only the start and end counts.
Can a population growth rate be negative?
Yes. If the ending population is smaller than the starting one, the rate is negative, showing the annual pace of decline.
How long until a population doubles?
Roughly, divide 70 by the annual percentage rate. At about 1.7% a year, a population doubles in approximately 40 years.
Related Calculators
Methodology & Review
The growth rate is the compound annual rate between the population at the start and end of the period. It assumes steady growth and does not model migration or year-to-year shifts.
Written by Ugo Candido · Last updated May 17, 2026.