WASHINGTON DC: US consumers spent $109.3bn online in Q4 2016, representing an 18% increase on the same period in 2015, the latest estimates have revealed.

According to comScore, the cross-platform measurement firm, desktop accounted for the majority ($86.6bn) of US retail e-commerce spending during the quarter.

That was an increase of 13% compared to Q4 2015, but the ever-growing reach of mobile was one of the key findings in the comScore report.

Online spending via smartphones and tablets reached $22.7bn in the final quarter of last year, which equated to year-on-year growth of 45%, or more than three times the growth rate recorded by desktop.

Overall, mobile accounted for 21% of total e-commerce spend in Q4 2016, which comScore said was mobile's highest recorded share of online sales for a single quarter since the company began measuring m-commerce in 2010.

"The mobile share of digital commerce dollars grew considerably from 17% a year ago and from only 4% in Q4 2010," the report noted. "Smartphones and tablets have become increasingly important to online buying with every succeeding year," it added.

Looking specifically at the holiday sales season in November and December 2016, comScore further calculated that $80.2bn was spent online, up 17% year-on-year.

That included $63.09bn via desktop, up 12% from the same period in 2015, and $17.12bn via mobile devices, which represented an impressive 44% increase over the year.

With m-commerce accounting for 21% of the holiday season's total digital sales, up from 17% in 2015, comScore stated the figures confirmed that more people have become "comfortable" making their holiday purchases on their mobile devices.

Data sourced from comScore; additional content by Warc staff