Population projections

A population projection gives a picture of what the future size and structure of the population by sex and age might look like. It is based on knowledge of the past trends, and, for the future, on assumptions made for three components: fertility, mortality and migration. Projections are not forecasts. They will differ from actual future outcomes to a greater or lesser extent. Many factors influence future patterns of births, death, and migration, including policy changes and unforeseen events such as weather events or epidemics.  In the coming years these may have a lasting effect and significantly influence population trends, but any projections cannot take these factors into account.

East Sussex County Council

East Sussex County Council carry out our own population projections, based on the ONS’s mid-year population estimates, births, deaths, and migration data. Our locally produced figures are also based on future new housing plans provided by districts and boroughs, which is why they are labelled “dwelling-led”. They inform local service planning in East Sussex.

Demographic projections briefing May 2025

Office for National Statistics

Subnational population projections

These projections give potential future populations for all English local authorities and health geographies. They are based on previous population trends, but they do not include local housing plans like our ESCC projections. These projections should be used if you want to compare with other local authorities.

Subnational population projections: 2022-based – Office for National Statistics

National Population Projections

National population projections (NPPs) provide an indication of the potential future population size of the UK and its constituent countries. These statistics are widely used in planning, for: economic and fiscal forecasts; health; education; pensions. The Office for National Statistics (ONS) normally produces NPPs for the UK and its constituent countries every two years.

The 2022-based projections, which were released in January 2025 have been produced using a new set of demographic long-term assumptions for fertility, mortality, and migration.  These are derived from analysis of past trends and through consultation with independent academic experts.

National population projections table of contents – Office for National Statistics

Economic forecasts

The Office for Budget Responsibility (OBR) produce regular economic forecasts.

HM Treasury publish a regular comparison of independent forecasts for the UK economy.