Holiday shoppers are buying more gifts over the internet this year. A new study estimates that online retail spending shot up 25 percent.

During the first 45 days of the holiday season, market research firm comScore Networks estimates online retail spending reached $19.48 billion. The figure in the same 2005 period was $15.57 billion.

Retailers have been aggressive this year with their online marketing efforts, targeting consumers with early-season promotions, said Gian Fulgoni, chairman of comScore Networks.

Online stores are continuing to promote, Fulgoni said, temping consumers to continue shopping with guarantees of on-time delivery for items purchased as late as December 18.

On Monday, December 11, consumers set a single-day record for online spending with $661 million, the firm reported. Two days later, that record was broken as consumers spent $667 million online. The data indicates growth rate versus year ago rose toward the end of the week, demonstrating that consumers are continuing to shop online later this season.

Last week, online spending rose to its highest point of the year, said Mr. Fulgoni. Several records were set, including the highest single-day of e-commerce spending ever on Wednesday, December 13 when consumers spent $667 million online, up 29-percent versus the corresponding day last year.

Sales estimates from November 1 to December 15, 2006 do not include online retail travel spending, auctions and large corporate purchases.

Correction: An article on Monday, December 18, 2006 about a comScore Networks report for online retail spending during the holiday season incorrectly stated that sales from November 1 to December 15 in 2005 reached $15.73 billion. The correct sales figure reported by the firm is $15.57 billion.