New figures from the Department for Work and Pensions show that almost one in six of us currently alive in Britain will live beyond 100 years.
Pensions minister Steve Webb said: "Many millions of us will be spending around a third of our lives or more in retirement.”
The DWP figures, based on Office of National Statistics (ONS) projections, raise concern over the urgency of possible strains on the NHS caused by the ageing population.
Of the ten million expected to reach their 100th year, 2.2 million are already over 50. Fifty years from now, over half a million people are expected to be aged over 100, compared to just 12,000 now.