This Commons Library briefing paper is a guide to understanding UK migration statistics. It explains the concepts and methods used in measuring migration and setting out a range of data on migration in the UK and in European Union countries.Jump to full report >>
There are two main ways of measuring the migration of people: 1) flows across an international border, and 2) the stock of people living in a particular country who are not nationals of that country or who were born abroad.
The number of people migrating to the UK has been greater than the number emigrating since 1994. For much of the twentieth century, the numbers migrating to and from the UK were roughly in balance, and from the 1960s to the early 1990s the number of emigrants was often greater than the number of immigrants. Over the last twenty-five years, both immigration and emigration have increased to historically high levels, with immigration exceeding emigration by more than 100,000 in every year since 1998.
This note explains the concepts and methods used in measuring migration. It contains current and historical data on immigration, emigration and net migration in the UK. It sets out the most recent estimates of the UK’s foreign national and foreign-born populations, and includes international comparisons of migration and migrant populations in European Union countries.
In the year ending December 2017, work was the most common main reason for immigration (43%), while formal study was the second most common main reason (30%).
There has been a fall in work-related migration since June 2016 which is accounted for by a fall in EU nationals migrating to look for work.
Study was the most common main reason for immigration during the period 2009-12, and the reduction in the number of people migrating to the UK to study since then reflects a reduction in the number of Tier 4 student visas issued to students from outside the EEA and Switzerland.
There are fewer foreign nationals living in the UK than there are people born in other countries. Between January 2017 and December 2017 there were approximately 6.0 million people with non-British nationality living in the UK and 9.2 million people who were born abroad.
The UK’s migrant population is concentrated in London. Around 36% of people living in the UK who were born abroad live in the capital city. Similarly, around 38% of people living in London were born outside the UK, compared with 16% for the UK as a whole.
After London, the English regions with the highest proportions of their population born abroad were the West Midlands (13.7%), the South East (13.6%), and the East Midlands (12.9%). In each of these regions the proportion of people born abroad was lower than for England as a whole (15.7%), which is skewed by London.
Of all the nations and regions of the UK, the North East had the lowest proportion of its population born abroad (6.2%), followed by Wales (6.3%), Northern Ireland (7.4%), and Scotland (9.0%).
The available data suggests that in 2017 there were around 785,000 British nationals living in other EU countries excluding Ireland, while there were around 3.8 million EU nationals living in the UK.
A migrant can be broadly defined as a person who changes their country of usual residence. Conventionally, there are three different ways of making this definition more precise.
A migrant can be:
Each of these definitions has its strengths and weaknesses. In practice, each of these definitions is used in certain circumstances, depending on the data in question.
In migration statistics, stocks refer to the number of migrants usually resident in a country during a particular period, while flows refer to the number of people changing their country of usual residence during a particular period.
Immigration and emigration are therefore flow measurements, recording the number of people entering and leaving the country on a long-term basis.
Statistics on stocks and flows are based on different definitions of a migrant.
Stocks are normally measured as the number of people whose country of birth or nationality is different from that of the country in which they live (the first two definitions above).
Flows are normally measured as the number of people changing their country of residence for at least a year (the third definition).
In the UK, data on stocks and flows comes from different sources. Stocks are measured through surveys of the resident population, while flows are measured primarily though surveys of passengers arriving and leaving the country.
Net migration is the difference between immigration and emigration: the number of people moving to live in a particular country minus the number of people moving out of that country to live elsewhere.
If more people are arriving than leaving, net migration is a positive number, which means net immigration. If more people are leaving than arriving, net migration is a negative number, which means net emigration.
A migrant is someone who changes their country of usual residence. An asylum seeker is someone who does so “from fear of persecution for reasons of race, religion, social group, or political opinion”. In this sense, asylum seekers are generally counted as a subset of migrants and are included in official estimates of migrant stocks and flows.