User guide to population projections

1. What are population projections?

While population estimates provide a picture of the population as it was last year, population projections provide a picture of the population as it may develop in future years.

Population projections provide an indication of the size and age/sex structure of the future population if specified assumptions about future fertility, mortality and migration were to be realised. They are not forecasts and do not attempt to predict the impact that future government policies, changing economic circumstances or other factors (whether in the UK or overseas) might have on demographic behaviour.

Back to table of contents

2. Who produces them?

National population projections (NPPs) are produced by the Office for National Statistics (ONS). These provide projections of the size and structure of the population of the UK, and of its constituent countries, for the next 100 years.

Lower level 'sub-national' population projections (SNPPs) are produced for local authority districts and similar administrative areas and are usually produced for the next 25 years. Lower-level projections for England are produced by ONS, for Wales by the Welsh Government, for Scotland by the National Records of Scotland (NRS) and for Northern Ireland by the Northern Ireland Statistics and Research Agency (NISRA).

Both national and sub-national projections tend to be produced every 2 years. In recent years, projections have been based on the even numbered years e.g. 2008-based, 2010-based and 2012-based.

We have also produced population projections by legal marital status and opposite sex cohabitation for England and Wales (available at England and Wales level only). Projections by marital status do not follow a regular timetable but are produced on an adhoc basis, the latest set being the 2008-based projections. They are generally available for up to 25 years ahead.

Back to table of contents

3. How are population projections used?

The primary purpose of the projections is to provide an estimate of future population that is used as a common framework for planning in a number of different fields.

The NPPs are used as a base for other official population projections such as marital status projections, subnational projections, household projections and in the calculation of life tables. Other government departments use the projections directly to calculate information such as future school place requirements, expected future cost of state pensions and potential demand for health services.

The SNPPs are used for planning services and to estimate future need, for instance in the provision of education, healthcare and social services. For example, the Department for Communities and Local Government has in the past used the SNPPs for England as an input into the funding formulation for local authorities, as well as an input to the official household projections, used to help regional house planning and monitoring.

The marital status projections were used by the Department for Communities and Local Government as an input into the number and type of households in England. They are also used by the Department for Work and Pensions to cost various aspects of the future social security programme. They are also of interest to other government departments, local government, commercial companies, special interest groups, academia and the general public.

Back to table of contents

4. Methodology

The following reports outline the methods used to produce the population projections.

Methodology for producing the NPPs

Methodology for producing the SNPPs for England

Methodology for producing the marital status population projections for England and Wales

Back to table of contents

5. Quality

The following documents provide a range of information describing the quality of the data, including points that should be noted when using the population projections.

Quality and methodology information for NPPs (290.9 Kb Pdf)

Quality and methodology information for SNPPs for England (216.3 Kb Pdf)

Quality and methodology information for marital status projections for England and Wales (156.1 Kb Pdf)

Back to table of contents

6. Published statistics

The release of the projections is announced on the UK National Statistics Publication Hub. Additional supporting information is usually published alongside the release of data including, for example, a statistical bulletin or summary reports detailing the methods and data used.

The latest releases of population projections are available via the following links:

National population projections

SNPPs for England

SNPPs for Wales

SNPPs for Scotland

SNPPs for Northern Ireland

Population projections by marital status for England and Wales

Back to table of contents