Population Growth Calculator

Population Growth Calculator

Enter the initial population size (e.g., 1000)
Enter the annual growth rate as a percentage (e.g., 5 for 5%)
Enter the number of years for the growth calculation (e.g., 10)

This population growth calculator estimates how a population changes over time based on various factors such as birth rates, death rates, and migration.

Suppose a city has an initial population of 100,000 and experiences a 2% annual growth rate. Using the population growth calculator, you can determine that after 10 years, the population would grow to approximately 121,899 people, assuming consistent growth.

Population Growth Calculation Chart

YearInitial PopulationGrowth RatePopulation IncreaseFinal Population
1100,0002%2,000102,000
2102,0002%2,040104,040
3104,0402%2,081106,121
4106,1212%2,122108,243
5108,2432%2,165110,408

Population Growth Formula

The basic formula for population growth is:

P(t) = P₀ × (1 + r)ᵗ

Where:

  • P(t) is the population after time t
  • P₀ is the initial population
  • r is the growth rate (as a decimal)
  • t is the time period

Using our previous example:

  • P₀ = 100,000
  • r = 0.02 (2% expressed as a decimal)
  • t = 10 years
P(10) = 100,000 × (1 + 0.02)¹⁰ = 121,899

How do you calculate population growth rate?

To calculate the population growth rate the formula is:

r = (P(t) / P₀)^(1/t) - 1

For example, if a town’s population increased from 50,000 to 65,000 over 5 years:

  • P₀ = 50,000
  • P(t) = 65,000
  • t = 5 years
r = (65,000 / 50,000)^(1/5) - 1
r ≈ 0.0539 or 5.39% per year

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