Analysis by Prudential also reveals nearly one in five (18 per cent) of those planning to retire this year will be below the poverty line.
The Joseph Rowntree Foundation estimates that to be above the poverty line a single pensioner in the UK needs an income of at least £8,254 a year, yet Prudential calculated 18 per cent of those retiring in 2013 expect to retire on less than this.
The findings also highlight a significant gender divide, with 21 per cent of women expected to retire below the poverty line in 2013 compared with 14 per cent of men.
In addition, women are nearly three times more likely than men to have no other pension - 23 per cent of women retiring in 2013 will retire without a private pension, compared with just 8 per cent of men.
The state pension accounts for 43 per cent of average retirement income for women in 2013, while the average man retiring this year will receive 30 per cent of his income from the state.
Prudential’s research showed nearly a quarter (23 per cent) of people retiring this year overestimate what the state pension pays by more than £600 a year, and 10 per cent have no idea how much it pays.
Vince Smith-Hughes, retirement income expert at Prudential, said: “Against a backdrop of rising living costs, the basic state pension alone is not nearly enough to provide a comfortable standard of living.
“While it is a very valuable source of additional income for millions of pensioners, the state pension should ideally only represent a part of someone’s retirement income, not all of it.
“Relying on the state will see many people retiring below the poverty line this year, which shows the importance of building up a personal pension.
“Virtually everyone with the option of a company pension should take advantage of that, and the tax relief and employer contributions that go with it. When combined these often come to more than double the amount of pension contribution the employee has to make.
“If people want to enjoy a comfortable retirement, saving as much as possible as early as possible is important, while seeking advice from a financial adviser or retirement specialist can also help to make the most of retirement income.”