Women retiring this year are nearly three times as likely as men to have only the state pension to live on, according to a report.
Some 20% of women, who often take career breaks or work part time to support families, said they have no other pension provision, compared with 7% of men, the research by insurer Prudential found.
The research, carried out among more than 1,000 people intending to retire in 2014, also found that nearly one in five (18%) people will have an income below the "minimum income standard" as defined by the Joseph Rowntree Foundation (JRF).
The JRF estimates that a single pensioner needs an income of at least £8,600 a year to reach a minimum socially acceptable standard of living; a retired couple needs an annual income of more than £12,500.
Across Britain, people expecting to retire this year in the North East and South West are the most likely to rely on the state pension, with 20% of people in both these regions saying they will have no other pension.
This year's retirees in the North West will be the least reliant on the state pension the survey predicts, with just 8% entering retirement without any private pension savings.
On average, people thought the state pension would make up around 35% of their expected retirement income, which is the same proportion that is typically expected to come from company pension schemes.
The state pension typically makes up 42% of a woman's expected retirement incomes compared with 28% for a man.
The findings follow a series of shake-ups announced by the Government for the pensions industry in recent weeks, which aim to prevent people being placed into workplace pension schemes with high charges as reforms to automatically place people into pensions are rolled out.
The Government has also announced measures to make it easier for people to cash in their pension pot when they retire, rather than having to buy an annuity, which usually guarantees someone a fixed income for the rest of their life. Annuity rates have plunged in recent years and there have also been concerns about people not shopping around properly to get the best annuity deal.
Vince Smith-Hughes, a retirement income expert at Prudential, said: "The changes to pensions and how people can take their retirement income announced in the Budget last month will provide savers and retirees with more choices.
"However they don't alter the fundamental fact that many people are not saving enough for a comfortable retirement."
Here are the percentages of people who said they will be retiring this year without a private pension, by region:
:: North East, 20%
:: South West, 20%
:: Wales, 16%
:: South East, 15%
:: Yorkshire and the Humber, 15%
:: West Midlands, 14%
:: Eastern, 13%
:: East Midlands, 12%
:: London, 12%
:: Scotland, 9%
:: North West, 8%
:: UK average, 14%
(Northern Ireland sample size was too small to include in the regional breakdown)