Population of the UK 1990-2021, by generation

In 2021, there were approximately 14.4 million millennials in the United Kingdom, making it the largest generational cohort at that time. Millennials surpassed the Baby Boomer generation as the largest generation for the first time in 2020. Generation X are as of 2021 the second-largest generation here at 14 million people, with their parent's generation, the Silent Generation numbering around 5.5 million people in 2020. As of that year, there were estimated to be 267,430 people who belong to the Greatest Generation, the parents of the Baby Boomer generation, who lived through major events such as the Great Depression and World War Two.

Post-war baby boom

The baby boomer generation was the largest generation for much of this period due to the spike in births that happened after the Second World War. In 1947 for example, there were over 1 million live births in the United Kingdom, compared with just 657,038 live births just thirty years later in 1977. This generation are typically the parents of millennials, and were the driving force behind the countercultural movement of the 1960s, perhaps due to their large numbers relative to older generations at the time.

Largest age groups in the UK

The most common single year of age in the United Kingdom in 2020 was 55, with approximately 938,738 people this age. People aged between 50 and 54 were the most numerous age group quintile in this year, at approximately 4.6 million people. In 2020, the median age of the UK population was 40.4, compared with 37.9 in 2001, indicating that like many developed countries, UK society has been getting older overall.