Bargain-mad Brits spent £197 each shopping in sales over the past year and felt like they wasted £53.
Collectively, £865 million was blown on purchases consumers came to regret, according to research by comparison site MoneySuperMarket.
In fact, some 27% of shoppers admitted they wish they hadn't bought at least one of the sale items they bought over the 12-month period.
The biggest causes of regret given were snapping up cheap impulse buys and purchasing things they never used.
Bargain-hunters in the West Midlands came to regret their purchases the most (34% expressed remorse), while the Welsh were the most satisfied (17%) with their sale shopping.
Across the UK, 18 to 34-year olds showed the most buyer remorse with 41% admitting to buying something they regretted over the last year.
Dan Plant, consumer finance expert at MoneySuperMarket, said: "It's all too easy to be blinded by the perceived bargains when shopping in the sea of red sale signs, but Brits need to try to keep some perspective about which deals are crackers, and which ones are duds."
He added: "Consumers should think twice before they make impulse buys that they might later regret. Splashing out on things you don't need or won't use is a waste at the best of times – but wasting cash right after the high spend festive period just to say you've bagged a bargain could be really painful during January's annual financial gloom."
The research also found that men actually spent more money on sales shopping than women during the period, with their shopping sprees coming with a total price tag of £212 compared to women's £185.