👪 Presets

Rapid growth

Ageing society

Replacement

Baby-boom echo

Vital rates

Total fertility rate: 2.10 Life expectancy: 72 yr Net immigration: 0.0 /1000/yr Time step: 5 yr

Expansive

Stationary

Constrictive

Boom echo

Stats

Total population—

Median age—

Dependency ratio—

Growth rate—

Doubling/halving—

Shape class—

Year—

A cohort-component projection ages the population one step at a time. Each cohort shifts up by the time step and loses members to age-specific mortality. New births = (total fertility rate ÷ reproductive span) × women of childbearing age, split ~51/49 male/female. The pyramid shape tells the story: a wide base (expansive) means rapid growth; straight sides (stationary) mean replacement; a narrow base (constrictive) means an ageing, shrinking society.