The 2021 Northern Ireland Census marked the first time since records began where the Catholic share of the population was larger than the combined Protestant share. In 2021, over 42 percent of the population classified themselves as Catholic or from a Catholic background, in comparison with 37 percent classified as Protestant or from a Protestant background. Additionally, the share of the population with no religion (or those who did not answer) was 19 percent; larger than any individual Protestant denomination. This marks a significant shift in demographic and societal trends over the past century, as Protestants outnumbered Catholics by roughly 2:1 when Northern Ireland was established in the 1920s. Given the Catholic community's historic tendency to be in favor of a united Ireland, many look to the changing religious composition of the population when assessing the potential for Irish reunification. Religion's historical influence A major development in the history of British rule in ireland was the Plantation of Ulster in the 1600s, where much of the land in the north (historically the most rebellious region) was seized from Irish Catholics and given to Protestant settlers from Britain (predominantly Scots). This helped establish Protestant dominance in the north, created a large section of the population loyal to the British crown, and saw a distinct Ulster-Scots identity develop over time. In the 1920s, the republican movement won independence for 26 of Ireland's 32 counties, however, the six counties in Ulster with the largest Protestant populations remained part of the UK, as Northern Ireland. Following partition, structural inequalities between Northern Ireland's Protestant and Catholic communities meant that the Protestant population was generally wealthier, better educated, more politically empowered, and had better access to housing, among other advantages. In the 1960s, a civil rights movement then emerged for equal rights and status for both sides of the population, but this quickly turned violent and escalated into a the three-decade long conflict now known as the Troubles.

The Troubles was largely fought between nationalist/republican paramilitaries (mostly Catholic), unionist/loyalist paramilitaries (mostly Protestant), and British security forces (including the police). This is often described as a religious conflict, however it is more accurately described as an ethnic and political conflict, where the Catholic community generally favored Northern Ireland's reunification with the rest of the island, while the Protestant community wished to remain in the UK. Paramilitaries had a large amount of support from their respective communities in the early years of the Troubles, but this waned as the conflict progressed into the 1980s and 1990s. Demographic and societal trends influenced the religious composition of Northern Ireland's population in these decades, as the Catholic community had higher fertility rates than Protestant communities, while the growing secularism has coincided with a decline in those identifying as Protestant - the dip in those identifying as Catholic in the 1970s and 1980s was due to a protest and boycott of the Census. The Troubles came to an end in 1998, and divisions between both sides of the community have drastically fallen, although they have not disappeared completely.

The population of Northern Ireland was 1.92 million people in 2023, compared with 1.83 million ten years earlier in 2013. Since 1971, the population of Northern Ireland has increased by approximately 380,000 people.

This dataset provides Census 2021 estimates for the number of usual residents in Northern Ireland. The dataset also shows the population density, as well as the size of the geographical area. The estimates and area boundaries are as at census day, 21 March 2021.

The census collected information on the usually resident population of Northern Ireland on census day (21 March 2021). Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on census day. Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc. The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.

To find out how Data Zones and Super Data Zones have been developed, and how other Northern Ireland geographies can be approximated, please read the notes here

The quality assurance report can be found here

These statistics contain the first phase of main statistics results from Census 2021. This phase provides estimates for a number of census topics, including passports held, ethnic group, national identity, language, and religion.

Data are available for Northern Ireland and the 11 Local Government Districts.

Dataset Name: Demographic data from 2021 CensusData Owner: NISRAContact: census@nisra.co.ukSource URL: https://build.nisra.gov.uk/Uploaded to SPACE Hub: 03/07/23Update Frequency: Per censusScale Threshold: some data has 10k threshold appliedProjection : Irish GridFormat: Esri Feature Layer (Hosted) Vector PolygonAbstractThe census collected information on the usually resident population of Northern Ireland on Census Day (21 March 2021).Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on Census Day.Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc.The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.Disclosure control methodsStatistical disclosure control (SDC) refers to a range of methods that aim to protect individuals, households, businesses, and their attributes from being identified in published information.NISRA has taken steps to ensure that the confidentiality of respondents is fully protected.All published results from the census have been subject to statistical processes to ensure that individuals cannot be identified. These processes may result in very marginal differences between tables for the same statistic.For Census 2021, NISRA is applying two strategies - targeted record swapping (TRS) and cell key perturbation (CKP), to ensure individuals are protected from identification while minimising the impact on the quality of results.Disclosure control methodologyFor more information, please refer to:Statistical disclosure control methodologyMethodologyThe census questionnaire including the questions asked and the administrative procedures involved in collecting the census data underwent substantial testing. Coding of the data was subject to quality checks.The quality of the results was improved by the use of edit and imputation procedures for missing or incorrect data, and the data were adjusted for over and under-enumeration.The outputs reflect the complete usually-resident population of Northern Ireland.Methodology overviewFurther information on the methodology used in Census 2021 is available in the:Census 2021 methodology overviewQuality issuesThe census results underwent an extensive quality assurance process, which included checks against administrative data sources and information on particular groups such as students and HM Forces personnel.Edit procedures were applied to obviously incorrect responses (such as someone aged 180) and were designed to correct the mistake by making the least possible change to the data.Imputation procedures were applied to missing data on a returned questionnaire, and drew on responses to the question from people with similar characteristics.Quality assurance reportFurther information on the quality assurance processes used in Census 2021 is available in the:Census 2021 quality assurance reportStatement about data qualityFor more information on data quality, including response rate and item response rate, please refer to the:Census 2021 statement about data qualityGeographic referencingIrish National GridNational Statistics publicationCensus statistics are produced by the Northern Ireland Statistics and Research Agency free from political influence and have been assessed as National Statistics by the Office for Statistics Regulation.Office for Statistics RegulationMore information is available on the following web site:Office for Statistics RegulationProducing census statisticsCensus 2021 statistics meet the highest standards of trust, quality and value and are produced using standards set out in the statutory Code of Practice for Statistics.Code of Practice for StatisticsMore information is available in the:Code of Practice for StatisticsDate of publicationJune 2023Further informationCensus 2021 results webpage

In 2023, there were 130,936 people aged between 55 and 59 in Northern Ireland, which was the most of any age group in this year.

Between 1821 and 1921, the entire island of Ireland was a part of the United Kingdom of Great Britain and Ireland, after both islands were united by the Act of Union in 1800. This graph shows only the population of the six counties of Ireland that would go on to become Northern Ireland. The population was just under 1.4 million in 1821 and grew to 1.7 million in the next twenty years.

Between 1845 and 1849 the Great Famine devastated the overall population of Ireland, causing the deaths of approximately one million people, and causing a further million to emigrate. Although the famine affected the population of the west and south of Ireland much more severely than the north, the population of the six counties still fell by over 200,000 people between 1841 and 1851. The population then continued to fall, reaching it's lowest point in the 1890s where it was 1.2 million. The Northern Irish population then grows slowly until the mid to late 1900s, during which time the state of Northern Ireland was founded in 1921. The population the reaches over 1.54 million in the 1960s, before it falls again in the 1970s. This drop in population coincides with the outbreak and the most violent decade of the Troubles in Northern Ireland, which was a conflict that dominated Northern Irish daily life for decades. However, from 1981 onwards the population grows by 70,000 to 12,000 every ten years, surpassing it's pre-famine level in the 1990s.

This dataset provides Census 2021 estimates that classify usual residents in Northern Ireland by single year of age, and by sex. The estimates are as at census day, 21 March 2021.

The census collected information on the usually resident population of Northern Ireland on census day (21 March 2021). Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on census day. Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc. The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.

Population estimates relate to the population as of 30th June each year, and therefore are often referred to as mid-year estimates. They are used to allocate public funds to the Northern Ireland Executive through the Barnett formula and are widely used by Northern Ireland government departments for the planning of services, such as health and education. These statistics are also of interest to those involved in research and academia. They are widely used to express other statistics as a rate, and thus enable comparisons across the United Kingdom and other countries. Furthermore, population estimates form the basis for future population statistics such as population projections.

This dataset provides Census 2021 estimates that classify usual residents in Northern Ireland by their religion. The estimates are as at census day, 21 March 2021. The religion classification used is a 32-category classification corresponding to the tick box options and write-in responses on the census questionnaire with at least 1,000 responses.

The census collected information on the usually resident population of Northern Ireland on census day (21 March 2021). Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on census day. Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc. The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.

This table reports responses for which there are 1,000 or more usual residents.

'Religion' indicates religion, religious denomination or body. 'Catholic' includes those who gave their current religion as Catholic or Roman Catholic.

Description of Data Notes: The estimates are produced using a variety of data sources and statistical models. Therefore small estimates should not be taken to refer to particular individuals. The migration element of the components of change have been largely derived from a data source which is known to be deficient in recording young adult males and outflows from Northern Ireland. Therefore the estimates are subject to adjustment to account for this and, while deemed acceptable for their use, will not provide definitive numbers of the population in the reported groups/areas. Further information is available in the Limitations section of the statistical bulletin: NISRA 2023 Mid-year Population Estimates webpage Time Period Estimates are provided for mid-1971 to mid-2023. Methodology The cohort-component method was used to create the population estimates for 2023. This method updates the Census estimates by 'ageing on' populations and applying information on births, deaths and migration. Further information is available at: NISRA 2023 Mid-year Population Estimates webpage Geographic Referencing Population Estimates are based on a large number of secondary datasets. Where the full address was available, the Pointer Address database was used to allocate a unique property reference number (UPRN) and geo-spatial co-ordinates to each home address. These can then be used to map the address to particular geographies. Where it was not possible to assign a unique property reference number to an address using the Pointer database, or where the secondary dataset contained only postcode information, the Central Postcode Directory was used to map home address postcodes to higher geographies. A small proportion of records with unknown geography were apportioned based on the spatial characteristics of known records. Further Information NISRA Mid-year Population Estimates webpage Contact: NISRA Customer Services 02890 255156 census@nisra.gov.uk Responsible Statistician: Shauna Dunlop

Description of Data Population estimates for the 3,780 Data Zones in Northern Ireland were published on 29th May 2025. Time Period Estimates are provided for mid-2021 to mid-2023. Notes: 1. Estimated populations are given as of 30th June for the year noted, rounded to the nearest person. 2. Rounding for estimates at this geographic level is independent. As such, figures may not add to higher geography totals. Methodology The population estimates for small geographical areas are created from an average of two statistical methods: the ratio change and cohort-component methods. The ratio change method applies the change in secondary (typically administrative) data sources to Census estimates. The 2023 small geographical area estimates use a single statistical dataset which has been created by amalgamating a series of different administrative data sources. This statistical dataset is a de-duplicated admin based estimate for the usually resident population of NI. The cohort-component method updates the Census estimates by ‘ageing on’ populations and applying information on births, deaths and migration. An average of both methods is taken and constrained to the published population figures. Further information is available at: NISRA 2023 Mid-year Population Estimates webpage Geographic Referencing Population Estimates are based on a large number of secondary datasets. Where the full address was available, the Pointer Address database was used to allocate a unique property reference number (UPRN) and geo-spatial co-ordinates to each home address. These can then be used to map the address to particular geographies. Where it was not possible to assign a unique property reference number to an address using the Pointer database, or where the secondary dataset contained only postcode information, the Central Postcode Directory was used to map home address postcodes to higher geographies. A small proportion of records with unknown geography were apportioned based on the spatial characteristics of known records. Further Information The next estimates of the population for Northern Ireland will be released later in 2025. Contact: NISRA Customer Services 02890 255156 census@nisra.gov.uk Responsible Statistician: Shauna Dunlop

National and subnational mid-year population estimates for the UK and its constituent countries by administrative area, age and sex (including components of population change, median age and population density).

Principal projection for Northern Ireland - population by five-year age groups and sex.

Population estimates relate to the population as of 30th June each year, and therefore are often referred to as mid-year estimates. These population estimates provide population totals for the 4,537 Small Areas in Northern Ireland and therefore can be used as building blocks for population estimates for higher level geographies.

United Kingdom Population: Northern Ireland: Male: Aged 85 to 89 data was reported at 8.801 Person th in 2017. This records an increase from the previous number of 8.556 Person th for 2016. United Kingdom Population: Northern Ireland: Male: Aged 85 to 89 data is updated yearly, averaging 5.000 Person th from Jun 1971 (Median) to 2017, with 47 observations. The data reached an all-time high of 8.801 Person th in 2017 and a record low of 3.000 Person th in 1980. United Kingdom Population: Northern Ireland: Male: Aged 85 to 89 data remains active status in CEIC and is reported by Office for National Statistics. The data is categorized under Global Database’s UK – Table UK.G004: Population: Northern Ireland.

This dataset provides Census 2021 estimates that classify households in Northern Ireland, with at least one usual resident, by household size. It also includes an estimate of the number of usual residents living in households and average household size. The estimates are as at census day, 21 March 2021.

The census collected information on the usually resident population of Northern Ireland on census day (21 March 2021). Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on census day. Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc. The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.

Average household size is a calculation of the usually resident population living in households divided by the number of households.

The quality assurance report can be found here