The forecast comes from the respected Conference Board, one of the arbiters of consumer spending data in the US.
The Board said the average US household would spend $483 on presents, up from $462 in 2001.
Shold the prediction prove correct, the spending spree might help set off what is expected to be particularly weak sales in the runup to Thanksgiving, the holiday due on Thursday 28 November.
Americans have customarily taken advantage of the holiday to open their wallets for the start of the holiday season.
But the lateness of this year's festival - held on the fourth Thursday in November - means shops have spent even more of November than usual waiting for the tills to start ringing.
Discounts
The additional spending expected before Christmas, the Conference Board believes, is likely to be triggered by aggressive cost-cutting as shops struggle to recoup their weak November.
"Despite widespread reports that worried consumers will sharply curtail their holiday spending, the board's annual survey projects a 5% increase in Christmas shopping this year," said Conference Board consumer research chief Lynn Franco.
"Continued discounting by retailers, both online and in the stores, is likely to prop up Christmas spending."
As is usually the case at the holidays, the Conference Board found that Christmas is much more expensive for poorer families than rich ones.
While families with an income of more than $50,000 a year said they would spend an average of $649, those on less than $15,000 planned to spend $233.