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.

In 2024, there were 130,736 people aged between 35 and 39 in Northern Ireland, which was the most of any age group in this year.

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

This dataset provides Census 2021 estimates that classify usual residents in Northern Ireland by ethnic group.

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 the categories for which there are 10 or more usual residents. Where there are fewer than 10 usual residents for any category, these have been reported in a residual group which may or may not contain 10 or more usual residents in total.

All ethnic groups are classified within one of the five groups: White, Asian, Black, Mixed, and Other. 'Irish Traveller' is included in 'Other'; this is changed from Census 2011 when 'Irish Traveller' was included in 'White'.

Quality assurance report can be found here

The population of Northern Ireland was 1.93 million people in 2024, compared with 1.84 million ten years earlier in 2013. Since 1971, the population of Northern Ireland has increased by approximately 387,500 people.

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.

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

In 2024, Belfast was the local district which had the highest number of inhabitants in Northern Ireland, with an estimated population of 352,390, followed by Armagh City, Banbridge and Craigavon which had approximately 222,511 people living there 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.

The National Population Database (NPD) for Northern Ireland is a point-based Geographical Information System (GIS) dataset that combines locational information from Ordnance Survey Northern Ireland (OSNI) with population information about those locations, mainly sourced from Northern Irish government statistics. The points represent individual buildings allowing the NPD NI to provide detailed local analysis for anywhere in Northern Ireland. The Health and Safety Laboratory (HSL) working with Staffordshire University originally created the NPD for Great Britain in 2004 to help its parent organisation, the Health and Safety Executive (HSE), assess the risks to society of major hazard sites e.g. oil refineries, chemical works and gas holders. Of particular interest to HSE were ‘sensitive’ populations e.g. schools and hospitals where the people at those locations may be more vulnerable to harm and potentially harder to evacuate in an emergency. The data for the NPD NI includes residential, schools and colleges, hospitals and workplace layers. The NPD NI was created using various datasets from OSNI and government organisations and contains other intellectual property so is only available under a license and for a fee. Please contact the HSL GIS team if you would like to discuss gaining access to the sample or full dataset.

This table provides Census 2021 estimates that classify people by Country of birth (12 categories) by Religion (8 categories) for Northern Ireland. The table contains 96 counts.

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.

Notes

1. 'EU' is the European Union and is as defined on census day (21 March 2021).
2. People who gave 'Cyprus' as their country of birth are included within the 'Europe: Other EU countries' category.
3. 'Europe: Other Non-EU countries' includes United Kingdom (part not specified) and Ireland (part not specified).
4. 'Religion' indicates religion, religious denomination or body.
5. 'Catholic' includes those who gave their current religion as Catholic or Roman Catholic.

Quality assurance report can be found here

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 2024 Mid-year Population Estimates webpage Time Period Estimates are provided for mid-1971 to mid-2024. Methodology The cohort-component method was used to create the population estimates for 2024. This method updates the Census estimates by 'ageing on' populations and applying information on births, deaths and migration. Further information is available at: NISRA 2024 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

Principal projection for Northern Ireland including population by broad age group, components of change and summary statistics.

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).

Period life expectancy by age and sex for Northern Ireland. Each national life table is based on population estimates, births and deaths for a period of three consecutive years. Tables are published annually.

Report describing the quality of mid-year population estimates in Northern Ireland using comparator data sources and demographic analysis Source agency: Northern Ireland Statistics and Research Agency Designation: Supporting material Language: English Alternative title: Northern Ireland Mid Year Population Estimates Quality Report