US online retail sales are expected to grow to US$294 billion this year, with nearly a third of the total from mobile devices.
Forrester Research said it sees online sales growing at a pace of 9.5 percent from 2013 to 2018, which would bring total online sales to US$414 billion, or 11 percent of all retail sales.
This year, mobile commerce — sales on phones or tablets — are likely to hit 87 billion, according to Forrester.
"The web keeps doing what it has always done well: it provides huge assortments of products, at comparable, often lower, prices than physical stores, with 24/7 access and often free shipping," said research analyst Sucharita Mulpuru.
Mulpuru said the figures include 30 retail categories, "and that doesn't even include another US$28 billion in additional mobile transactions on sites and apps like Uber and Domino's Pizza that aren't even in that aforementioned mobile commerce number."
Mulpuru, in a blog post, said the growth in e-commerce does not mean traditional brick-and-mortar retailing is dead.
"Yes, old store concepts located in B and C centres are absolutely in peril but new fresh concepts in A properties are doing quite well," she said.
"While there are dying shopping centres that need to be razed and reconstructed as office parks or farmland or whatever, there are malls, even indoor malls, which are doing absolutely fine."