This emerged in new research from savings and retirement specialist LV= of over 4,000 consumers.
Reduced spending on commuting, childcare, eating out or going on holiday has enabled 72% of people to put money by.
The average saved was nearly £5,500, but 8% reduced their spending by more than £10,000.
UK consumers are split on what they are doing with these savings - 10.6million have put it in savings or cash ISAs, 8.2million are going to go on holiday and 7.4million are using it for home improvements.
Longer-term savings are proving less popular, with only 5% saving extra into a pension.
Clive Bolton, managing director of savings and retirement at LV=, said:
"Our research indicates that much of the accumulated saving has been concentrated among relatively well-off households.
"The UK has been divided into two groups - those who are struggling on reduced incomes, and those whose income has remained stable and whose costs have been greatly reduced.
"The past 12 months has been tough for many, especially for those who have been put on furlough, made redundant or who are self-employed.
"However, those people who have remained in work have been able to save large sums as large expenses such as holidays, commuting costs, childcare and entertainment have vanished."
Meanwhile, another study has found Britons have used lockdown to enter the world of investment.
Halifax Share Dealing discovered that 16% of young people aged 18 to 24 took their first steps into stocks and shares since the start of the pandemic.
When it comes to reasons for this surge, having more spare time was the main factor.
Almost a quarter say they have more time to research options and 16% have more time to arrange investments. Having more disposable cash is also a factor for 17% of Britons.
Staying at home over the last 12 months has also influenced existing investors.
Almost one in four have increased their investments since the start of the pandemic. Despite this boost in engagement with the stock market, one of the biggest barriers for those who have not started is the fear of losing money, which is putting off 39% of people - up 6% from last year.
This is followed by not knowing enough about the stocks and shares market (34%) – a jump of 5%.
The research has also highlighted a gender gap in attitudes, with more women than men hesitant to dabble in stocks and shares.
