Bargain hunters plan to splash out £1.8bn more on the January sales than they did last year, a survey from insurer Direct Line suggests.
Many shoppers have been waiting all year for the start of the sales
More than £5.5bn will be spent by Britons during the sales, it claims.
In preparation for the shopping binge, 2.7 million Britons asked for shopping vouchers as Christmas presents.
Londoners are set to spend the most in the sales, about £171 each on average, while people in Wales estimate that they will spend nearer £73 on average.
Direct Line surveyed 2,300 Britons to find out their spending intentions during the sales, and the survey comes at a time when the amount of outstanding consumer debts has been climbing quickly.
The findings of the Direct Line survey seem to be bear out the initial post-Christmas news from retailers.
Retail analysts Footfall reported that the number of shoppers visiting top stores across the UK on Tuesday was up 7% on last year.
Selfridges reported first-day sales 14% higher than a year ago, while the Trafford Centre near Manchester saw sales 3% up on last year.
Business group the CBI said that sales had been better than expected in the early run-up to Christmas.