The latest unofficial estimate from the Office for National Statistics (ONS) for the number of people living in the UK in March 2025 is 69,708,000, which is on track to reach just over 70,000,000 people by the end of September.

Our chart of the week looks at how the UK population has changed over the past quarter of a century, from 58.9m, 60.5m, 62.9m, 65.2m and 66.8m in September 2000, 2005, 2010, 2015 and 2020 respectively to an extrapolated 70.0m for September 2025.

The net increase in each five-year period is 1.6m, 2.4m, 2.3m, 1.6m and a projected 3.2m to September 2005, 2010, 2015, 2020 and 2025 respectively, equivalent to average annual increases of 0.5%, 0.8%, 0.7%, 0.5% and 0.9%.

The net increases comprised somewhere in the region of 3.5m, 3.9m, 4.0m, 3.7m and a projected 3.4m births, less approximately 3.0m, 2.8m, 2.9m, 3.1m and a projected 3.4m deaths plus net inward migration estimated to be 1.1m, 1.3m, 1.2m, 1.0m and a projected 3.2m in the five years to September 2005, 2010, 2015, 2020 and 2025 respectively.

The large jump in net inward migration in the past five years has been the principal driver of an acceleration in the point at which the population is anticipated to reach 70m. This was projected to occur between 2028 and 2030 in 2010- to 2016-based principal population projections produced by the ONS, before a sharply declining birth rate pushed this out to 2032 and then 2038 in the 2018- and 2020-based projections. The anticipated date was then accelerated to 2027 in the 2021- and 2022-based principal population projections as the post-Brexit rise in immigration started to become apparent.

With births and deaths expected to mostly offset each other over the next five years, the UK population in September 2030 will depend almost entirely on the level of net inward or outward migration over the next five years. The last central projection from the ONS was for net inward migration of around 2.0m over that period, based on net inward migration falling to 340,000 a year by 2027, consistent with current economic and fiscal forecasts from the Office for Budget Responsibility (OBR). 

Of course, forecasts are almost always wrong and so the UK population is probably not going to be exactly 72.0m by September 2030. However, subject to a major revision to recent estimates of the actual numbers of people living in the UK, it does seem very likely that the UK population will reach 70.0m at some point this year.