Brick-and-mortar stores still claim the lion's share of shopping dollars, but e-commerce is continuing to close the gap as Americans increasingly turn to online shopping as a channel for their holiday season purchases, a report shows.

Measured by dollars spent, consumers anticipate doing an average of 38 percent of their holiday shopping online in 2016, according to The NPD Group's 2016 Holiday Purchase Intentions Survey.

A whopping 71 percent of consumers—and 79 percent of millennials—plan to do some of their holiday shopping online this year, according to the online survey of 3,499 U.S. individuals aged 18 and older conducted in September 2016.

"Online continues to change the game for retailers because it goes beyond convenience by bringing value and timing into the equation," Marshal Cohen, chief industry analyst for The NPD Group, said in a release. "Brick-and-mortar retailers still have the benefit of drawing the majority of holiday shoppers with the in-store experience, but it is clear they are going to have to put their best foot forward in order to maintain a hold on the holiday 2016 and future seasons."

Online shoppers will buy mostly the same products as in-store shoppers, but the online buyers spend more. E-commerce consumers anticipate spending an average of $710 this holiday season, roughly 60 percent more than the $440 those sticking with stores plan to spend, the NPD survey showed.

Other trends show that consumers are increasingly going online to learn about the products they're on the hunt for, doing online research using consumer reviews and social media. Shoppers are also using their phones for more than just research. Fourteen percent of U.S. shoppers—including 29 percent of Millennials—say they'll use their mobile phones to buy gifts this year, a jump of 130 percent over last year.

"We are at a point where retail must embrace the online shopping culture, not just try to battle it, especially during the critical holiday shopping season," added Cohen. "There are opportunities to be had in the relationship between brick and click—maximizing the emotional component of shopping in-store, while utilizing the convenience and flexibility of shopping online, will create a complete shopping experience for the consumer and a happy year-end for retail."