The statistics also showed one in eight (13%) of those polled admitted they did not have any pension savings.
When it came to looking ahead to funding later life, more than a third (36%) had never estimated their income needs for retirement, which Aegon says puts them at “significant risk of being unable to maintain their existing lifestyle.”
Just over a quarter (26%) of the 946 respondents, who were polled in May, said that they did not know how much they held in pensions, with the figure increasing to 38% for those aged 65 and over.
A modest 17% of those aged 55 to 64 held more than £300,000 in pension savings – the amount that someone on average earnings would need to maintain their current lifestyle in retirement.
Steven Cameron, pensions director at Aegon, said: “These figures should set alarm bells ringing.
“Despite the introduction of auto-enrolment, there are still many individuals who are entirely unprepared for retirement.
“Many people may put off finding out how much they have saved, fearing it will be less than they’d hoped or will need.
“But however unsettling, the earlier you carry out a reality check, the more chance you have of doing something to get back on track.
“It’s worrying to see that many approaching retirement age don’t know how much they have saved for retirement and only one in five are on track to maintain their lifestyle.”