Use this estimator for a transparent scenario based on an explicit base population and stated fertility, mortality, migration, or interpolation assumptions.

Census count

Population enumerated at the census date.

Census date

Census reference date in ISO form YYYY-MM-DD.

Target date

Target date such as the mid-year point in ISO form YYYY-MM-DD.

Growth rate

Assumed constant annual growth rate in percent for the interval; supply the observed or assumed value.

Elapsed days

Whole days between the census and target dates.

Elapsed years

Elapsed time in years using a 365.25-day year.

Mid-year population

Mid-year equivalent population from exponential interpolation.

A projection is conditional, not a prediction. Uncertainty increases with the horizon, and discontinuities in migration, boundaries, policy, fertility, or mortality can invalidate the assumed path.

Run multiple scenarios and compare them with a cohort-component projection when the necessary fertility, mortality, and migration schedules are available. Sensitivity ranges are more useful than a single extrapolated path.

• Headship Rate Household Projection

  Project the number of households with the headship-rate method: multiply each age group's adult population by its age-specific headship rate and sum across groups.

• Postcensal Intercensal Estimator

  Produce a postcensal estimate by the component method (base plus births minus deaths plus net migration since the census) or an intercensal estimate by linear interpolation between two censuses at a stated fraction of the interval.

• School Age Population Projection

  Project a school-age cohort to the next planning date with the census survival ratio method: survivors equal the current cohort times l(x+n)/l(x), plus net school-age migrants.