Census 2021: Everything you need to know
What is the census?
The UK census is a national population survey that takes place every ten years. It aims to collect detailed data from every household in England, Wales, Scotland, and Northern Ireland, helping to create an accurate snapshot of society at a specific point in time. The 2021 Census was the most recent, offering a vital record of how the UK population has changed over the past decade.
In England and Wales, the Office for National Statistics (ONS) is responsible for planning and delivering the census. In Scotland, it is conducted by the National Records of Scotland (NRS), and in Northern Ireland by the Northern Ireland Statistics and Research Agency (NISRA). Together, these organisations build a unified picture of the UK population in 2021, using standardised questions and methods to ensure consistency across all four nations.
Is the UK census mandatory?
Yes, taking part in the UK census is a legal requirement. The Census Act 1920 makes it compulsory for residents in England and Wales to complete the census accurately. Failure to do so, or knowingly providing false information, can result in a £1,000 fine and a criminal record.
That said, not all questions on the census are mandatory. Questions related to religion and sexual orientation are optional, allowing individuals to leave them blank if they prefer.
How often is the census conducted?
The UK census is held every 10 years, typically in the spring. The 2021 Census took place on Sunday 21st March 2021, with the previous census conducted on 27th March 2011. Census Day is widely publicised to ensure full national participation and consistent data collection.
Since the first census in 1801, the UK has carried out a census every decade — with the only exception being in 1941, during the Second World War. Once collected, all census data is anonymised and protected. The actual census records remain confidential for 100 years before being released to the public for historical and genealogical research.
The 2021 results revealed several key trends: an overall increase in the population, greater ethnic diversity, and changes in religious affiliation and home ownership. There was also a notable rise in the number of people aged 65 and over, as well as an increase in car and van ownership across the UK.
What topics are covered in the 2021 Census?
The 2021 UK Census collected a broad range of information to better understand the social, economic, and demographic makeup of the UK. Topics included:
Demographic information such as age, sex, and household composition
Migration patterns and country of birth
Ethnic group, national identity, language spoken at home, and religious affiliation
Health and disability status, including long-term conditions and unpaid care responsibilities
Type of housing, occupancy rates, and ownership
Employment status, industry, job roles, and travel to work patterns
Education levels, qualifications, and school attendance
Sexual orientation and gender identity (new for 2021)
Whether respondents are UK armed forces veterans
These areas provide a full picture of life in the UK and help organisations respond to social and economic changes.
What is census data used for?
Data collected in the census has a wide range of applications. It helps government departments, local councils, charities, businesses, and researchers make evidence-based decisions.
Local authorities rely heavily on census data to plan and deliver vital public services. This includes education, transport infrastructure, healthcare provision, and housing development. For example, population growth in a particular area may influence decisions on school funding, NHS capacity, or public transport investment.
Businesses also benefit from census insights. Demographic and economic data helps companies understand local markets, identify suitable locations for new branches, and tailor their services to meet customer needs. A retail chain might use census employment data and travel patterns to determine where to open a new store.
Voluntary and community organisations use census data to understand the needs of their communities. The information can support funding bids, highlight areas of deprivation, or identify trends in health and care that inform local support services.
Academics and students regularly use census datasets in social and economic research. The census provides one of the most reliable sources of large-scale population data in the UK.
For the general public and genealogists, census records offer a window into the past. Historical census data, released after 100 years, allows people to trace their family history and understand how previous generations lived, moved, and worked.
When was 2021 Census data released?
Census 2021 data was published in multiple phases, beginning in Summer 2022 and continuing into 2023. The Office for National Statistics released results in stages to allow users to digest and explore the findings in detail.
The first phase included rounded population and household estimates for England and Wales, broken down by age, sex, and local authority.
Later phases introduced more detailed information, including multivariate data that allowed for comparisons across multiple variables (e.g. employment status by ethnicity or religion by age). Additional releases covered alternative population bases, small population groups, flow data (also known as origin-destination data), and microdata samples for researchers and analysts.
Can I map census data?
Yes. Census 2021 data is available in a variety of formats, including interactive maps, tables, and downloadable datasets. These tools allow you to explore how population characteristics vary by area — from local neighbourhoods to regional and national levels.
If you’re interested in working with census data visually or geographically, you can book a demo to explore our mapping solutions and learn how to use Census 2021 data for research, planning, or decision-making.