Rising adoption of smartphones and tablets helped U.S. commerce grow 81% last year to nearly $25 billion, according to a new eMarketer report. The research firm projects that total will increase another 55% this year to $52 billion and reach $86 billion by 2016.

Shopping on tablets in particular will take off, accounting for nearly half ($24 billion) of projected m-commerce sales in 2013, and twice that amount by 2015.

Retails sales via smartphones will grow more slowly, increasing 36% to $13.4 billion this year and $24.3 billion by 2016.

Tablets alone will drive 9.4% of all retail e-commerce sales in 2013, with smartphones accounting for 5.3%. Those figures will grow to 16.9% and 6.7%, respectively, in the next four years.

Purchases through e-readers and other mobile devices will make up a much smaller share of overall m-commerce and online sales.

Mobile devices accounted for 11% of total U.S. retail e-commerce sales in 2012, with that share expected to grow to 15% this year. eMarketer notes that its m-commerce estimates excludes sales of travel and event tickets. They are drawn from an analysis of 120 data sets from dozens of third-party research sources tracking commerce sales and consumer behavior.