An estimated five million shoppers will go online and spend £103.6 million, an average of around £20 each, on Christmas Day, according to the IMRG.
According to internet research firm IMRG, £84 million was spent online on Christmas Day last year, but the year-on-year increase this year is expected to be more than 15%.
Retailers are already preparing to maximise their Boxing Day Sales. John Lewis Direct managing director Robin Terrell said: "Our aim is to make sure that John Lewis is there for our customers in ways that suit their lifestyles. As part of this goal we are for the first time ever starting our online Clearance on Christmas Eve."
Hitwise UK managing director Robin Goad said: "Christmas Day and Boxing Day are becoming more important for online retailers every year. Last year for the first time ever, Boxing Day was the busiest day for online retailers bar none, while online retail traffic also increased by 44% between Christmas Eve and Christmas Day. Given the current hunger for bargains, it seems likely that both days will be even busier this year."