Rolph Population Sandbox

Population & Timeline

Start population

Start mean age

Years to simulate

Up to 100,000. Slider syncs with the number box; internal sampling keeps the chart responsive.

Log scale (min=1)

Mortality

Mean life (years)

Max age

Survive to 40 (1 in N)

≈ 0.556%

Survive to max age (1 in N)

≈ 0.100%

Checks: S(40)=—% · S(80)=—% · mean≈—y

Fertility

Birthing age start

Birthing age stop

Average kids per girl

Window=27y · births per fertile girl≈0.452/yr

Catastrophic event

Enabled

Every N years

Kill fraction (%)

Starts at year

Applied at end of the year (after births & natural deaths) by removing a fraction across all ages.

Start year

—

Population health

—

Reset

Welcome

Welcome to Rolph population simulator.

Simulate population growth over any given time period.

Try to keep growth within a healthy target.

Population over time Max

Linear Y‑axis: −100,000 .. selected max (chooser in header). Toggle log if the line hugs the floor. Hover for Year, Pop, plus B/D this year and totals.