Worries about the environment are driving shoppers away from Boxing Day sales, with spending expected to drop by around £200 million this year.
High Streets are also facing tough competition from online retailers like Amazon and BooHoo as people browse and buy from home on their phones rather than on cold pavements.
Around 40 per cent of UK adults will take advantage of the post Christmas sales, and spending is expected to total around £3.7 billion according to Barclaycard.
A total of 62 per cent of men and 68 per cent of women have said they will be buying less for the sake of the planet.
Almost seven in 10 consumers also plan to spend less on “fast fashion” because of the potential environmental impact of its production.
The predictions will cause alarm at the end of another tough year for the beleaguered UK retail sector.
Store closures, business failures and job losses have continued as online has continued to drive growth and competition in the sector.
Barclaycard, which processes nearly half of all credit and debit card transactions in the UK, said Boxing Day spending was 4.8 per cent higher in 2018 than 2017, but a record Black Friday this year could mean that shoppers may have already made the majority of their purchases.
Just 33 per cent said they planned to spend more on Boxing Day than they did during the Black Friday and Cyber Monday sales.
Online spending is also predicted to overshadow in-store receipts, with 60 per cent of post-Christmas sales shoppers making the majority of their purchases from the comfort of their homes.
Rob Cameron, chief executive of Barclaycard Payments, said: “Despite Boxing Day remaining a key moment in the retail calendar, savvy shoppers have been planning their large purchases throughout the entire festive sales period, which begins long before December.
“Our data for Black Friday and Cyber Monday revealed a huge jump in transaction volumes this year, so it’s not surprising that consumers expect to have less money to spend after Christmas, so retailers need to take that into account.
“What’s more, our research shows that shoppers are increasingly thinking about how their purchases impact the environment. Forward-thinking retailers should be making a conscious effort to demonstrate their commitment to sustainability, in order to boost their appeal – and their revenue.”
VoucherCodes.co.uk and the Centre for Retail Research have also predicted that shoppers will shun the high street on Boxing Day, with in-store sales set to drop by more than 12 per cent on last year.
The study suggests that in-store spending will total £3.25 billion – a decrease of 12.4 per cent on last year – while online spending increases by 10 per cent year on year.
Consumers had shown signs of “promotional fatigue” for the last two years after the “many” discount events by Boxing Day, including Black Friday.
The report says: “We expect the numbers attending the sales to reduce. However, it is anticipated that average spending per household in the sales will still be around £459.”
Opinium Research surveyed 2,002 UK adults online for Barclaycard between November 29 and December 3.