Population Projection

Adjust the parameters below to explore how population and number of children change over time.

Settings

Start populationParent fractionWhat fraction of the population are parents (0 - 1)Kids per coupleAverage number of children per coupleGenerationsNumber of time steps to simulateLifespan (years)How long individuals liveYears per generationHow many years constitute one generationDeath rate per generation (0 - 1)probability that an individual dies in a generation, e.g., 0.1 means 10% die each generation

After 12 generations (~396 years), projected population is 30.

Total children born over this period: 939.

Total people died over this period: 1,909.

How this model works

Start population is the number of people alive at generation 0.
Parent fraction is the share of the current population that becomes parents. From these parents we form couples and apply kids per couple to get new children in that generation.
Generations is how many times this birth/death step is repeated. Each generation advances time by years per generation, which defines the spacing on the X axis.
Lifespan removes any cohort once its age reaches the chosen number of years. These removals appear in the red deaths line.
Death rate per generation removes an additional percentage of the alive population every generation, on top of lifespan-based deaths. The graph shows births (amber), deaths (red), and total alive population (purple) over time.